i know this might sound kind of simple, but it helps me alot to get the most tips possible.
Ok, first, just grab the bottle of beer and toss it at a wall, then let it bounce into ur hand...continue the process until ur whole meter is full.
Second, of course, just use his special and throw bottles like crazy, once it's done, wait till u've served around 6 customers and repeat the process again
This will ensure that u get maximum tips from most of the customers...after u've used the special, make sure to mix they're drinks as fast as possible and just keep throwing the beer bottle around to get their meters higher.
The further u throw the bottles, the more they're meter will go up, same with the special meter