- As written, neutral fighters can become knights at 9th level. You get nothing for being a knight, other than having to do what your king tells you. Compare that to what lawful and chaotic fighters get, and the knight quickly looks pretty lame. If paladins and avengers get neat tricks, knights should get them too. Maybe look at AD&D's cavalier for ideas?
- Dump the cleric and the magic-user as written. Put all their spells into a pile, then divide them into "white" and "black" magic. Write two new classes - let's call them "magician" and "sorcerer" for now - based around those revised spell lists. Make sure neither of them are armored holy fighting guys... that's what the paladin does.
- Rework thief skills somehow.
- Either let the demihumans reach the same level as humans using the optional rules in the appendix, or drop them entirely. None of this half-assed "enforce a human-centric world by dicking over non-human player characters" garbage.
- Give elf characters access to the druid's spell list, instead of the magic-user's.
- Either drop the druid, or make it a class you can enter at first level.
- Drop the mystic class. It's mechanically borked and doesn't really have the right feel anyway.
- Write up a ranger-type class - probably one without spellcasting abilities.
- Tone down weapon mastery a little, but KEEP IT. Maybe make it exclusive to fighters, or make it so knights get more masteries?
- Keep skills, but make the skill list about 75% shorter.
- Define alignments as sworn allegiances to the otherworldly powers of law or chaos. The vast majority of humans are neutral. Change the alignments of a lot of the monsters accordingly.
And that's just for starters! Judging from what I read of other people's "basic" D&D campaigns, I imagine the choices I'd make aren't the ones many would go with, but that's the beauty of houseruling.
(On an unrelated note, I got my DragonRaid boxed set yesterday. I haven't read any of its contents yet, but I can say that it is BIG.)