Kamard said:
Don't forget to make as many scrolls of your attack spells as you can, that way you can focus memorization on other spells.
I strongly disagree with this.
You make scrolls of the spells you would seldom use, but that are lifesavers when you hit that special circumstance.
A scroll of Magic Weapon, for when you hit something with DR and someone in the group doesn't have a magical weapon. "Here, I'll enchant that for you, so you can go kill the gargoyle."
At slightly higher level, a scroll of Tenser's Floating Disk for if a comrade goes unconcious and you can't cure them enough to so they can walk on their own. You want one at about 3rd caster level, so you can carry enough weight for a person.
Again at higher level, a scroll of See Invisible for obvious reasons.
At much higher level, a scroll of Dismissal to get rid of that extradimensional creature.
Scrolls take care of the spells that are special purpose and you will not always be using. You want to memorize the spells that you will always be using, doesn't cost any gold or experience points to do so.
Something I forgot to mention: At first level, a ray of frost is actually worth casting. At higher levels, the damage just isn't there. At first level, 1d3 is enough to seriously hurt many of the monsters.