Few house rules ...
Some house rules I found useful:
(Star Trek, CODA)
1) Skill maintenance...
Any character has to pay 1 development point for every non professional skill above 8 or loose the skill to 8.
So if Lieutenant Suvak has a skill of games chess at 10 he has to pay 1 point for 9 and one point for 10 in order to maintain his skill at that level, since that skill is non professional skill for him. This takes place at the time of advancement.
I found this rule useful in limiting super powerful characters that are able to maintain their skill levels regardless of their current service and posting. So, no more Starfleet engineers who are capable of armed combat skill of 12 without practicing...
2) Bonus to skill limit
At any time a bonus to the particular skill from edges, promotions or any other non skill points based bonus cannot exceed an actuall skill in value.
So Lieutenant's Suvak diplomacy skill is 4 he cannot obtain bonuses to that skill based on edges, promotions, profession tiers bigger that additional 4.
Basicly there is only so mach you can do with your knowledge.
I have discussed the above modifications with my players and have succesfully used them in our campaign. Everyone sees the logic in them and considers them fair.
To say that, it was my game, you are welcomed to try them in yours, or simply comment on them 
Kind Regards
Daniel
Captain Alexandra Polanski
CO, USS Archangel (flag of 7th Fleet, RRTF operations)