Here are three (or four?) more ways to demonstrate preselection.
This is a long term method. Go to the same club frequently, get to know the people there and pickup girls without this method just to get them to like you. Make whatever you want from these relations, fuck them, friendzone them, whatever, as long as you build healthy and positive relations. Once you have this social circle established, the next time you meet a stranger you will demonstrate preselection just by knowing the others in the club. A more short term method of the above is to bring female friends to the club.
Now for a method that you can perform during a night. Just mingle around and get to know people at the club for a couple of hours (it depends on how late you go out). Make sure that you contribute to every social interaction and make people happy. This way you make them want you to be with them, and they will tend to chase you, maybe say things like "hey, get over here". Such things demonstrate that you are a popular guy, and if it is a girl who does it you have successfully demonstrated preselection to others.
A final and more subtle or suggestive method... If you are alone and have not yet built a reputation like I described above you can (and this is probably the only almost mandatory thing) suggestively communicate preselection by having the abundance mentality. This is an inner-game-thing from RSD, and I think it is Julien's idea from the beginning:
http://www.pualingo.com/pua-definitions ... mentality/