There are a lot of different signs you can use. The important thing is to have a good indicator. That is, a sign that let's the players know that ofter this sign the next one is sign that is "live". That way you can go through several signs to keep the opponent from knowing what you are doind. I usually have my signs be the touching of things like my nose, ear, chin, hat, wrist and so on. A good way to give bunt direction is to use the side that your sign was given on. For instance, if touching your shoulder is your bunt sign, tell your players that if you touch your left shoulder they bunt to first and the right is bunting to third. Hope this was not too confusing.

Brian is right on, every coach has his own method. I like to use my belt for the hit run, guess I got that from my son, every time I took my belt off he ran.

http://seamusbaseball.blogspot.com/2009/08/signals-and-signs.html