Introduction
Made your force.
Got some spells.
Time to go blow shit up!
Stop. Stop right there.
Here's my suggestion if you want to do this: Play another game.
Phantasy Star Online is extremely biased against Force offense, as once you hit the Ultimate game, tech resistances are far too high to do decent damage, and there's the existence of damage cancel. (If two attacks hit at rougly the same time, one or all of damage is cancelled. The window of time for damage cancel depends on the players' latency to the server. The better, the less damage cancel.)
That being said, techs can be decent in the Episode 4 environment with the correct tech boosts (solo'ing only!), as can Simple techniques on a max-MST FOnewearl.
This guide will outline what you need to do be a good Force, and what you should do on each force to reach their maximum potential without slowing your team members down with techniques.
Each setup on a force (support, melee and nuking) should be utilised for the different situations your force will encounter, with support being the most important (and only requires pieces of equipment) then melee and then nuking (solo only for nuking). All you need to do to switch from a melee to a nuking setup is just change your units and mag with the correct material setup.
Starting as a Force
Recommendation: Do not make your first character a force. Doing this is counter-productive, as the new player has little meseta for fluids, which are required to do your jobs.
First things first, the force is a support class. No buts, no ifs. If you are preparing to play a Force, you must be prepared to support your parties. This is relatively easy to do, all you'll need is Shifta, Deband, Jellen, Zalure, Resta and Anti disks (I don't really recommend Reverser, but that will come later. I will leave a general tips section at the end).
To start off, (make sure you have your mind mag for technique learning, and techniques from your higher character (20+ supports recommended at least) find some friends, party up and level up by tagging each enemy with Zalure (and maybe Jellen if your party requires it). Doing this should net you quick levels, as you'll receive 80% EXP of all enemies in the room when they die. With the 3X EXP here, this should be relatively quick. Obviously this is very boring, but if you lack the proper equipment for force offense, it's the best thing to do for now.
And this is just the basics of being a good force. Join party, cast your supports, keep your party topped up on HP (unless there is a HUcast who knows how to use Dark Flow) and watch things drop dead.
Force Support
FOmarl > FOnewearl > FOmar > FOnewm. The tiers of support. But don't fret, being a FOnewm doesn't mean all is bleak. You're still able to support a party as well as a FOmarl or FOnewearl, it's just not as easy.
The general stages of support is: Shifta/Deband at start of quest (and during corridors! Don't let it run out), Zalure every spawn (Jellen if anybody suffers knockdown) and top of damage / berserk drops. As a random note, Jellen and Zalure cause DAMAGE CANCEL, and they are always the things to cancel (due to doing a damage of 0). Try to cast the two as fast as possible when a spawn spawns to minimize this.
In terms of equipment, every force should carry the following for supports (listed in terms of usefulness from left to right):
Clio (100% extra Zalure range) OR Dark Bridge (200% Extra Zalure range) OR Glide Divine (most useful, 100% to Jellen and Zalure range)
(Female Forces) Madam's Parasol and Madam's Umbrella (100% to Shifta/Deband / 100% to Resta/Anti) OR Striker of Chao and Marina's Bag (100% to Shifta/Deband / 100% to Resta/Anti) OR Tyrell's Parasol (most useful, 100% to Shifta/Deband/Resta; Anti range is not needed)
(Male Forces) Striker of Chao (100% to Shifta/Deband)
Support Merges for Resta and Shifta.
Learn to swap weapons (and shields) quickly for each situation. Equip your SD range increasers when you want to SD, JZ increasers when you want to JZ, etc. A party loves a support Force who can support well, and they also love forces who can use offense well...
Force Offense
Depending on the force you choose to play, your method of offense will be different (yet similar), as each class gets different equipment, while the ATP/ATA differences also differentiate the choices that you should choose.
Generally, FOmar/l and FOnewm use ATP offense (mostly Demon's, though, since this is better the higher HP targets) and FOnewearl exclusively uses Demon's offense (Si techs can be used to the finish the job, if you wish). To melee well, you will need good equipment, sphered in some cases (Excalibur, Rambling May, Vivienne, Diska of Braveman, etc...), sometimes with hit (not always, though. Despite FOs have low ATA, hit is not required that much) and definitely a set of Demon's equipment (Bringer's Rifle and Slicer of Fanatic).
To quote myself from another topic, here are the entire equipment sets I think a FO should have:
When melee'ing as a FO, be careful! Your damage will obviously be much, much less than other characters, which means you're just a damage canceller if you do not control your attacks. This means attack enemies which aren't being attacked, or Demon's them if all are being attacked (since 75% of total HP will always be more than the others are doing). Unlike techs though, melee can be controllable to avoid damage cancel, which is always good.
Demon's offense most of the time is recommended to actual offense if your party is good, as they'll be doing 99% of the damage, even if you try to intervene with your Rambling May or vulcans or whatever.
Force Nuking
Advisable only for Episode 4 solo, but may be neccessary on FOnewm/newearl for E1/2 maps (I don't recommend it if you can help it though). The power of nuking is large, but comes at a cost of large damage cancel in parties (parties will always kill faster than a solo FO nuke, though a solo FO nuke is faster than other classes in Episode 4).
For nuking, you will need the general nuking equipment, which is:
Summit Moon (+30% to Simple Techniques)
Magical Piece (+30% to Normal Techniques)
Psycho Wand (+30% to Hard Techniques)
Mercuricus Rod/Dark Bridge (+30%/+40% to Grants)
Demonic Fork/Dark Bridge (Piercing Megid)
The numerous merges (One for each attack technique, bar Grants/Megid, and one for each element, which is 10% weaker than the separate merges).
If you want to nuke well, you will most likely want to play a FOnewearl or a FOnewm. FOnewm gets a natural +30% boost to Gi/Ra techniques, while FOnewearl gets a natural +30% boost to Simple techniques AND EXTREMELY HIGH MST. When you are nuking, be sure to learn to switch weapons and shields quickly for maximum damage. Note: Generally, Rafoei is always better than Gifoei, but on certain spawns with Lizard/Merissas next, Gifoei can spawn damage these enemies, effectively cutting down on time.
In parties, attack techniques can still be useful if you use them correctly and not spam them. There are numerous uses, such as stunning things (lilies, Meris), stopping charges (Zu, Bringer, Spawning Dorphon/Delbiter) and other numerous uses (such as finishing off a Demon's strike). Megid is a good technique for certain Episode 2 enemies and Lizards in Episode 4, but otherwise it isn't recommended.
Other random tips
If possible, always wear a V801. This cuts down on casting time rather effectively. It won't look like much, but use it for a week and then take it off. It will feel slow. For example, V801 allows you to stunlock Gorans in desert if you keep them at range.
Adept is not recommended for TP Reduction, only stats on FOnewm/newearl. Generally, TP Reduction is useless as if you have 2,000+ TP, all you need to do is pop a Trifluid every five minutes or more (plus approximately 9% chance of finding one from an enemy when you kill it).
Solferino is not recommended for Resta spamming. You might think "Oh, free TP! Faster Resta casting!", sure. The problem with Solferino is it ignores all Resta boosts, including natural boosts. You'll see the boosted effects, but the Resta will not apply to your team members.
Always carry Moons. They are instantaneous and less dangerous than Reverser is. Sure, Reverser is free, unlimited revival, but if a Moon can do it faster, why bother? I only see Reverser as a spell if you run out of Moons.
Don't Rabarta spam to try and be useful. It's much better to just cast your supports and use Demon's, as if people want freeze, they can use Frozen Shooter, Rabarta themselves or Freeze Traps. Rabarta'ing alot will only cause damage cancel.
Don't Jellen Gal Gryphon unless you are with three very high level CASTs (sans HUcaseal) who have defense and HP. If you are with three high level casts, they will be combo'd regardless.
Do not try to do things pre-emptively as a FO (or try to be the first in rooms to do things). Always leave this to the HUs/RAs, as they can do starter things much better. You being first will only mess things up. (As I've learned recently. xD)
For certain Delbiter (4 Delbiter Spawn in PW4 20F) or Dorphon spawns (5 Dorphon spawn in MaxC E4), it's better to use Merc Rod gifoei to stop their charges rather than a normal gifoei, as this will allow RAs/HUs to use multi arrest weapons / freeze traps easier on the mobs.
May put more here...
I understand this guide is structured badly, but I do hope it helps somebody.
If you have any questions, please ask.