So before I ask anything keep in mind im on Ps3 so mods are off limits.

I have never played a mage in oblivion before and I want to start one. However im not sure what kind, I'm currently trying to pick between a build like the Imperial Battlemage I ran into who was wearing heavy armor and a hood, a cloth wearing pure mage or a light armor spellsword. Problem is i really have no idea how magic works in OB so I'm having a hard time choosing! What should i know before I make a build and what builds have worked out for you guys?

For a first mage, I'd suggest a Breton, with the Mage birthsign.

Magic is very versatile in the game. It's possible (although challenging) to play a "pure mage," who uses no weapons at all.

As for armor, it's a personal preference, but you should be aware that wearing armor reduces your spell effectiveness. It's not too big of a problem for some magic skills, like Destruction or Restoration, but it will be a big deal for Illusion magic later in the game. Armor is not actually a Battlemage skill, though; that would be more like Oblivion's default Spellsword or Sorcerer.

I rather like the default Battlemage, but I'd suggest that you create a custom class version of it, substituting Restoration for the Blunt skill, so you'd have:
Alchemy, Alteration, Blade, Restoration, Conjuration, Destruction, Mysticism for major skills.
I think I'd go with Intelligence and Endurance for favored attributes.

I'd equip the character with a good dagger (you can pick a silver one up from several mages guild halls, once you join), and I'd use it in conjunction with Alchemy (poison) for when an enemy manages to charge you. Your character can wear heavy armor, which will train up and give you advances in Endurance (better health) as you level up.

If this is your first mage, and you're not going to do any hardcoe RPing, I'd forget about the spell effectiveness and go with the armour. Weapon skills won't be that helpful if you're going with Destruction and Conjuration, just carry around a nice enchanted sword in case some enemy manages to close in.

Taking a dagger and going the Nightblade route is really fun too though, particularly with poison.

All in all, it doesn't matter, it's possible to succeed with any build.

Yeah I really liked the look of that Battlemage with his heavy armor topped off with a hood. Might just be the way I'm going. Also since I saw an Imperial Battlemage decked out in the sane gear it won't be a difficult RP. Just need to cone up with a story explaining how an Imperial Battlemage could wind up in prison.

Forgot to add, thanks both of you for your helpful responses

Yeah, a battle mage looks cool in armor. However, I can achieve a higher armor rating with a mage in street clothes: whether it be from spells, or enchanted clothing. And experience the bliss of 100% spell effectiveness, which is essential if you are using mind-control spells at high levels. Armor is good to wear (especially heavy armor) in the early levels, up until about level 12ish. Then start enchanting!
My current mage, an Altmer Apprentice, doesn't even use weapons anymore. That's right, all he carries is a staff for backup.

Now that sounds pretty awesom! I have something to work towards now