Brent Kelley, About Guide to Golf, offers these guidelines:
Tip the same as you would at a restaurant that has valet parking...$2 would be a good amount.
The equivalent of a hotel bellhop, a bag boy takes your golf clubs and sets them up on a golf cart for you when you arrive. Afterwards he removes your clubs, wipes them down and returns them to your car when the round is over. Tip a couple bucks on arrival; tip $5 after the round if your clubs/shoes were cleaned, or $2-$3 if not.
Most starters simply check you in at the first tee, maybe announce that it is your turn to play. Under normal circumstances, it is not customary to tip the starter. But if you show up without a tee time and the starter fits you in, pass him a few bucks. If you're staying at a resort for several days, check with the starter upon arrival and inquire about preferred tee times. If the starter sets aside your group's preferred times for the days you want to play, your group might tip from $50-$100 total.
The presence of caddies means you're playing a fancy course and expected to spend. So don't skimp on your caddie, if using one. Tip your caddie 50 percent of the caddie fee (adjusted up or down for quality of service). If there's a caddie master -- the person who assigns caddies to golfers -- ensure getting a good one by tipping the caddie master 20 percent of the caddie fee.
A single forecaddie works for one group of golfers. He doesn't carry bags but does keep track of everyone's shots and generally helps keep the round moving. A forecaddie should get one tip from the group, from $50-$100.
These guidelines are excerpted from About.com Golf's golf course tipping article.