Not to seem brash, but some of Thanee's suggested feats are no-nos.
Greater Spell Penetration? Are you joking? I mean, Spell Penetration is probably a tad over the top but a *second* feat to overcome the SR of those rare creatures which have it. IMC, we have three arcane spellcasters: not one has Spell Penetration.
Eschew Materials? Are you honestly suggesting that having to spend a full-round to cast a spell is worth the saving of not having to have a material component pouch? This is a wasted feat.
Instead, consider Improved Initiative. Mage-battles often boil down to Initiative, especially at higher-levels.
Go easy on metamagic feats: one or two could be handy, but be careful about them due to the full-round requirement. Empower, Maximise and Chain are usually pretty good bets. Definitely take Greater Spell Focus.
Prestige Classes: Consider Elemental Savant from Tome and Blood, or perhaps a few levels of Fatespinner. Both are very powerful.
As for frontline-sorceror, be careful. Dispel Magic can end your fun and your life. If you're insistent, Dragon Disciple is the way to go, but buffed-frontliners are better suited to combat clerics (divine favour, death ward, divine might, righteous wrath, recitation...). Artillerist is better.
Spellswise:
1st: Magic Missile, Shield, Mage Armour, Expeditious Retreat.
2nd: Melf's, any buff spells (starting with Eagle's Splendour), GLITTERDUST (often overlooked- blinds in a 10' radius and reveals invisible creatures)
3rd: Haste, Slow, Blink, Fly, one of Lightning Bolt/Fireball.
4th: Improved Invisibility, Polymorph Self/Other, Evard's Black Tentacles (overlooked but perfect vs. enemy spellcasters).
5th: Feeblemind, Dominate, Wall of Force, Cone of Cold
6th: Disintegrate, Antimagic Shell, Mass Haste, Tenser's Transformation if you're that way inclined
7th: LIMITED WISH (most useful spell of its level for sorcerors by a LONG way), Prismatic Spray, Teleport w/o Error, Forcecage.
8th: Horrid Wilting, Otto's Irresistable Dance, Maze, Polymorph Any Object (yes, it supersedes Poly Other, but PO is so powerful at its level that its obsolescence at ultra-level doesn't really matter, and PAO is both a great utility spell and combat spell)
9th: Time Stop, Imprisonment, Meteor Swarm, Energy Drain, Shapechange. NOT Wish: at 5000XP a hit, you will hardly ever want to cast it.