I would look into all the schools of magic and decide how you want to play. That's the first step. Typically most people focus on two schools that would compliment each other. For example, a pure destruction mage is nice if you never get hit by anything but you're screwed if someone gets in close.
Combo's that I like to use are Restoration/Desctruction, Destruction/Alteration, Illusion/Conjuration, and Conjuration/Restoration.
Staffs fit into combat that you have a powerful source of a certain spell to cast at any time, and you don't need to know that spell to use it. However, iirc having experience in the school it's associated with (fireball - destruction, summon flame atro - conjuration) helps in giving that staff's spell a bonus (someone check on this please?)
This game is nice for it's dual wielding, same can be done with spells. On top of that, two hands can equip the same spell and with a perk you can multiply the affect of the spell to be even more powerful if you were casting each hand seperately (like the spell flames, both hands can shoot a ray of flames by themselves, or together shoot a more powerful ray that is more powerful than the individual ones combined)
Spells don't level up as you level up, instead their effectiveness goes up the higher your rating is in that school (example, 50 destruction is more powerful than 25 destruction). As you get higher in levels though, your magika pool will increase so you can tap into those more demanding spells, plus there are perks that reduce the spell cost of novice, ameteur, adept, expert, and master level spells.
First thing is first, pick a style of play by reading up on the schools of magik and learn their spells and imagine how you would use them.
Also, just because you're a magic user doesn't mean you can't use weapons. Throw a couple perks into the first star on the one-handed tree and use some enchanted daggers too. Oh, that's the other thing. Learn how to enchant gear. Read up on soul trapping, soul gems, and enchanting. Sort of essential for magik users.
Good luck.