Not quite full, yet not quite shor handed.

I play a lot of home games with a bunch of friends, but most of the time we only have 4-7 players playing. What kind of changes preflop would be best to make in regard to starting hands?

For starting hand requirements, take a general starting hand chart. And remove UTG, UTG+1... etc until you've removed enough seats to match the table you currently play at...

Generally suited connectors and small pairs reduce in value from 6 people and less. And pairs about 7 and high connectors, face cards and aces shoot up.

-'rilla

I read Doyle Brunson's chaper in the Super System on Texas Hold'em just to find out it applies more in games with 8 people or so.

Mostly because he advises to play suited connectors and not to play AQ

In a shorter game, you want the highest cards possible. The value of connected cards goes down. In a four-handed game K9 is not such a bad hand! And when you hit your pair of Kings you might not be concerned about your low kicker, at least not as much as in a game with 8 people where playing K9 is practically suicide.