XP is not hard to come by in these games. If memory serves, you can hit max level in Pool of Radiance pretty easily. If you carry characters through, you can hit max level in, well, many of the games.
Something to bear in mind: each time you have the XP to train up a level, if it is at all possible, GO TRAIN. Unlike in later games, the Gold Box games had this annoying function that would actually "eat" your XP. Here's how it plays out.
Let's say you need 18,000 XP to go from level 9 to level 10, and 22,000 XP to go from 10 to 11, and 28,000 from 11 to 12. You enter a dungeon at Level 9, wander around in a dungeon for a while, loot some treasure, kill some monsters, etc. You earn 27,958 XP. Awesome! You'll go up two levels and be a hair's breadth from going up a third!
Except, no, you won't.
What the game will do is:
Level you from 9 to 10 and leave you with 22,001 XP -- just BARELY enough to get from 10-11. From 22,001 up to 27,958? That XP is just gone. Evaporated. Poof.
So, the better strategy is to try to train each time you have enough XP to go up ONE level, OR to train up IMMEDIATELY when you're able to go up 2 levels. In other words, if you get 18,153, train up. Your XP will stay the same. No worries. If you go up to 22,249, though, when you train from 9-10, your XP will be "shaved down" to 22,001. That gives you just enough to go from 10-11, but you won't keep any XP beyond the minimum required to go up to lvl 11.
Other things to keep in mind:
- The different races have some real pros and cons. Elves have great dexterity, as do halflings. Dwarves have great constitution, meaning they tend to have higher hitpoints. Half-Elves don't get stat bonuses, but can multi-class (actually, technically, half-elves can get 18/75 strength, whereas I think elves can only go up to 18/50, but I may be wrong). HOWEVER, most of the races are limited in terms of WHICH classes they can play, and also can be limited in terms of HOW FAR they can advance. If you plan to run a single party the whole way through, keep all of that in mind. You can always take extra levels in Thief, but you'll be capped in a multi-class character, depending on race, for things like Fighter or Mage or Cleric (where available). The Manual or the Adventurer's Journal details your racial limits. There are other factors that come into play, too, I think. For example, Elves cannot be resurrected. If they die, that's it. No rezzing at a temple (or in the field in the later games). I THINK that applies to half-elves, too. Halflings (I think) cannot equip some of the larger weapons (e.g. two-handed sword, longbow, most polearms). However, I think they're supposed to be harder to hit. Same with dwarves and gnomes (I don't remember if you can play a gnome, though). Humans have to play single classes (until Curse of the Azure Bonds where they can "dual class"), but
- Trolls are a major pain in the ass to fight, especially in the first two games, because they can regenerate. HOWEVER, damage done by fire (and, I think, general magic?) cannot be regenerated. So, if you get a flaming longsword, it'll kill a troll more easily. If you have firefan or fireball as spells, that'll kill 'em. One other handy trick is to have a character stand on the spot where the troll fell. This is kind of a cheap tactic, because, realistically, you'd expect the troll to just...get up and knock you down, but that's how the game works. This will be important in one of your toughest early fights.
- If you really want to cheese the game...take some characters, advance them a ways in the game, train them up, then go to a training hall and "Remove character from party" making certain to save them. You can then start the game anew...with your already leveled-up characters. They'll also keep whatever gear and treasure they had. This, too, comes in handy in Curse of the Azure Bonds, but you'll figure out why that is as soon as you load a Pool of Radiance party into the game and start it up...