Shield, identify and chromatic orb are good choices.
Protection from evil only if you intent to have no cleric in your party
Reflected image sucks. Use level 2 mirror image instead

Thanks. So Magic Missile, Sleep, Shield, Identify and Chromatic Orb are good choices from level 1, without missing anything too obvious or important?

Not sure who to go with yet - had thought about an 'evil' party in BG2, but in BG1 Jaheira will probably be on board, so that covers the cleric and protection from evil.

Jaheira is a fighter/druid. She has healing spells, but not protection from evil.

Yes, silly mistake by me, had forgotten her specs. Looked through the available NPCs, and either Branwen or Viconia should be good party members.

I normally use Branwen for my clerical needs until I can get beloved Yeslick, who is amazing at everything.

Magic Missile = has lots of counters and the Orb is a better spell.
Sleep = bg1 only and comes in a wand.
Shield = counters Magic Missile... does come in an item but still worth it because Magic Missile is used by so many mages to attack you... you won't use it much after bg1.
Identify = usful but there are lots of scrolls and an item at the start of bg2 that make it less so.

Chromatic Orb = stays useful all the way to tob.
Friends = nice for solo play... basic use it before shopping.
Sommon Farmilar = nice but you only need it once so use a scroll.
Protection from Petrification = VERY good spell in bg1 but pointless after that.
Larloch's Minor Drain = fast single shot Magic Missile that can heal you... if you don't have Chromatic orb or the target is imune to it then good for stopping him casting something at you but otherwise the orb is best.

Thanks, I've barely ever used the Chromatic Orb, but it's better as you level up a fair bit, right? I'm thinking about going for Shield next so I have some kind of defence in fights, and then Identify next, with Chromatic Orb as the 5th level 1 spell. Decent idea?
Never used Yeslick because he comes so late, and I prefer to get the team I will actually use earlier than that. I'm not sure how the transition to BG2 will work with BGT, but since I'm thinking about a somewhat evil party there, I'm thinking about going that route in BG1 too, so have plotted down these NPCs as interesting:

Sorcerer
Imoen
Viconia
Kagain
Edwin
Kivan

For instance, if I were to not dual Imoen in the BG1 section, would she be a pure thief in BG2 after the BGT transition?

Take any spell you like mate... and yes C-orb and Magic Missile both get better as you level, by bg2 c-orb will sometimes kill the target outright but the main point is that its fast and will always be a good opening spell.

Kivan is good so won't get along with that group... I'd suggest SHAR-TEEL as a fighter or you could dual her to thief as well but again its your game.

Interesting seeing the issues of certain spells being vital in one BG game but useless in the other or very different or present in one and gone entirely in the other. It's nice to have more variety in the spells than yet another magic missile but +1 damage than the last or more sparkles in the casting effect animation. Some of the best magic user builds in D&D used those sorts of spells as they could turn the tide of a battle more than blowing the magic missile load and doing a couple of points of damage that the fighter or anyone else could have done instead and then being useless until you sleep again. Use or lack of situations to use all the spells could be easily overlooked by developers, especially on a big project that is likely divided up into areas for different writers and designers.

Decided to install the full NPC Project mod once I was on it. Still annoys me from time to time, but some of the discussions between Kivan and Edwin and Viconia has been interesting. They have rather different approaches :D

Also installed a tweak that means characters won't break due to reputation, because with some evil characters that is bound to happen really, due to the limited "choices" in the game. Either you have to be somewhat sensible, which leads to rep going up, or act like a complete twat. As a result, Edwin constantly says something about the agreement being void and "Goodbye". He stays put though ;)

Not sure what Fezred is on about exactly, but one of the things I like with Magic Missile is that it can abort the initial spell by opposing mages (or sirines, which was quite the trouble - but in a good way). Sounds like C-orb can do much the same. An obvious limitation with sorcerers is that you only have a few different spells to choose from per level, but the positive is that it's more dynamic. If you want to fire off heaps of magic missiles you can, but if you want to identify a pack of items you can do that instead. Without lots of sleeping and re-organising spells in the book.

I'm not nearly experienced enough to know what is needed for the different fights, or even where what occurs, so I tend to play mages more generalist anyway, so therefore a sorcerer fits better for me.

One question: When playing with BGT, will the characters that re-appear in BG2 be the same as in BG1, with same spells and levels? So if I were to for instance keep Imoen a Thief the entire time, would she stay that way? What about Edwin and Viconia?

Got to level 11 and had to choose a lot of new spells, filling out some of the lowest levels. Hopefully not made too many clangers yet.

Level 1: Chromatic Orb, Identify, Magic Missile, Shield, Sleep
Level 2: Blur, Detect Invisibility (?), Melf's Acid Arrow, Mirror Image, Web
Level 3: Fireball, Melf's Minute Meteors, Minor Spell Deflection (new, unsure if decent), Protection from Fire
Level 4: Greater Malison, Spirit Armor, Stoneskin
Level 5: Breach, Lower Resistance

The innate ability of Vampiric Touch is pretty wicked. Never tried it before because I simply assumed it was crap, but the PC ended up in the 'ring' in the Coronet, fighting some bloke, and I tried it. Says I drained 28 HP from the victim, but my own HP went from 60 to 116, so double of 28. That's pretty wild stuff! Obviously all those extra HP are temporary, but almost a double (a lucky roll this time tbf) can mean the difference between being alive and dead.

I see Jan has a very high Detect Illusions ability (thief), is this a passive ability, so it will always be on, or does he need to be detecting traps to spot invisible creatures and such?

He will need search toggled on, yes.

Sweet! So when I get it up to 110 I don't need to have search for traps turned on? Could be useful in battle too then, without Jan being "inactive". Sort of an alternative to the very useful True Seeings of Keldorn (I don't use him).

Btw, is it worth it to put various spell triggers on a sorcerer? You can only choose so few spells after all.

It is passive but don't expect it to be as effective as actively searching: it takes a much longer time to detect things.

Just remember that a spell trigger is a one-shot thing, so you need to reset it each time it's used. I'm not big, or keen, on sorcerers, so maybe somebody else who is could give you better guidance.