The general idea would be look at your advantages & disadvantages compared to your enemy's.

Much of combat can really be whittled down to active abilities vs. passive abilities. Warriors, rangers, shapeshifters, even conjurers in a way tend to be better on the "passive" combat. Consider this how well you'd fare if you got up and walked away from your computer.

Things like invokers, transmuters, druids, shamans tend to fight using "active" abilities. Things you have to put in commands during combat to really accomplish much.

As a transmuter, this means you're going to want to avoid getting struck by "lagging" attacks. Most commonly bash/trip, though there's a plethora of others. Cranial, pincer, headbutt, neurological disruption, telluric surge, throw, crushing blow, etc etc. Otherwise, for defense consider many of the "buffs" transmuters get. Metabolic quickening, accelerate, stone skin, fly, pass door/control translucence, arcane absorption all provide means to help protect you that once cast, are active until the spell wears out. Many of which can help your parry abilities as well.

On the offensive side, you have both direct damage (mental jolt, disrupt XXX), "lag" attacks (neurological disruption, and so SOME degree things like disrupt organ), and debuffs (corporeal softening, metabolic slowing, etc). Reading the helpfiles should give you a general idea of each's primary use, though a lot of them also have secondary uses as well. This is where you have to look at who you're fighting.

If you're fighting a heavy-offense melee character, you'll probably want to make use of metabolic slowing early on to lessen the number of their attacks. Against an invoker, necromancer, shaman, or such, you're probably more concerned about their spells causing direct damage or debuff/maledictions. Here, you might want to consider lag attacks, or since many of those classes are just as frail as you are, maybe you can just trading off damage spells and hope you win. Here's where something like corporeal softening also improves your spell abilities.

As a transmuter, you have a LOT of options of buffs, debuffs, & damage options. Also, the fact that many of these have both positive & negatives, or secondary effects means there's a lot of details you can learn, but that should give you a pretty basic overall picture.