Here are some of the simple tweaks to the rules I've used in my game:
1) Astral construct - can only summon one at a time. No ectoplasmic armies without a prestige class or something.
2) Energy missile - +1 to save DC for every 2d6 augmented. In general, any time you see 1 power point augment resulting in +1 save DC or the like, I recommend you scale it 2 PP = +1 DC. That way it effectively scales the same way spells do.
3) Expanded Knowledge feat - you can only take this feat once. This helps keep the people from cherry picking all the cool powers they want from other disciplines. Sure you could grab energy missile at 5th level, but then you miss out on other cool powers later on.
4) Dispel Psionics - The augment affects the cap on the manifester level, not the manifester level itself. So no augment lets a psion go up to +10 without any problems, just like dispel magic. However, if an 11th level psion augments with an extra PP, this lets them get up to +11 on the dispel check, since the augment bumps the cap up to +12.
I personally haven't had anyone abuse schism or any of the empathic transfer powers, so I don't have any suggestions there. But in general, if you can think of the most conservative way to read any given section of text in the XPH, you should be fine. And if you run into any problems, folks around here are usually quite good and rather polite about offering suggestions.
Hope this helps and have fun!
Cheers,
Vurt