Welcome to third edition.
Are you going to be first level?
Assuming you are, I'd suggest playing an Elf sorcerer. That's what I did.

If that doesn't interest you, then ignore the rest of this long post!
Since you are a 2nd edition veteran, most of the spells should be familiar to you.
Sorcerers start the game knowing two first level spells, and 5 zero level spells (cantrips). You don't have (or need) a spellbook.
The table in the sorcerer section of the classes chapter of the players handbook shows how many spells per the day the sorcerer can cast. This is increased by having a high charisma - the relevant table is more or less at the start of the book, but basically assuming your charisma is at least 12 (and lower than something silly, like 24) the effect is you can cast one more 1st level spell than it says in the sorcerer table, due to your high charisma.
Unlike the wizard, he doesn't have to memorise (although the 3rd edition uses the term "prepare") spells in advance.
Thus, if your two first level spells known are
magic missile and
sleep, in any given encounter you can decide which is better to cast each round, until your spells per day are exhausted. Note that you can also use a higher level slot to cast a lower level spell - for instance if you have used all your zero level spell slots but you really need another
light spell, you can use up a first level slot to cast it.
Sorcerers live and die by their selection of spells known. Pick spells that you think you are going to use a lot at low levels. Opinions vary.
I'd suggest :-
0 level
detect magic, light, disrupt undead, prestidigitation, ghost sound
1 level
sleep, grease
You could take magic missile, but its pretty useless at 1st level - I'd wait until 3rd level (when you get to choose another 1st level spell known), and in the meantime use a bow.
Sleep requires a will save, but doesn't work on undead. Grease requires a reflex save but also has some non-combat uses.
The "must have" skill is concentration, as it allows you to cast spells when under pressure - note that taking damage whilst casting no longer automatically disrupts a spell; instead you get to make a concentration check. Hopefully its a skill you will never use - keep your sorcerer well away from trouble - but when you need it, you
really need it.
I also like giving sorcerer's the spellcraft skill (otherwise the
detect magic spell isn't so useful), and knowledge (arcana) might be useful.
Other than that, there aren't any other skills you need.
The simplest feat to take is improved initiative. That gets used all the time.
I'll happily fully stat up an elf sorcerer (or any other kind of sorcerer) for you if you want one.
Has your DM told you which books are allowed when designing characters? There are loads of 3rd edition sourcebooks out there, but some DMs prefer only to use the players' handbook.
How are ability scores to be generated? (Not every DM uses the 4d6 drop the lowest method.) If it is by rolling dice, you don't want me doing it for you as I get lousy results. [last character - 15,14,12,9,9,9]