I tip whenever I color up (cash out), and also place bets for them.
The best way to get the dealers to help you out thru the course of your action is to place bets for them. Throw a red chip down for the dealers on one of your bets. Pass line is usually pretty safe. But they seem to really like the bets on the hardways.
I would guess that about two or three times an hour I will place bets for them. Usually based on how they are treating me, how helpful.
If the table goes on a pretty good run, and there are a couple of people making bets for them, then it will add up fast.
When I place bets for the dealers, I always state "player control", which means I get to determine when the original bet is taken or left. For instance, I place a $5 chip on the pass line for them. We hit the number. They just rake the winnings and I have them leave the original $5 chip to keep the bet going. Unless you specifically tell them to let you have control, they are supposed to rake both the original bet and the winnings.
Last time in Vegas I was at a table that a guy rolled for 1 hour and 40 minutes. I know for a fact the dealers won a couple of grand on that one guy's roll. Almost everyone at the table was very experienced players and all were making bets.
When making bets for them, I always notice how much more helpful they become to not only you, but the other guys on your end of the table. Helping people with the correct amounts, etc.......