#3: adding to what has been said.
I'd say about 10% of the time, the dancer is working out some kind of bigger game and you won't get their interest. 20% of the time, the girl is just working a regular. The other 70%, the girl is tired or lazy and is taking it easy at a table. If not part of the first 10%, then the girl will likely be responsive.
The key is waiting for her to go on stage; so that she is separated from the regular, etc. I've done it before, myself. Plop down the $5, $10 or $20 (depending on club) on the stage and when she comes by say "I'd like a dance from you later." No need to be complicated. She will likely remember you. Otherwise, enjoy the stage dance. No need to stalk or anything :).
BTW, she will likely go to the dressing room first after leaving the stage. Normal. She is gathering her stuff and sorting out tips. Don't move too far from your stage-side seat or she might have a hard time finding you later.
The bigger question is whether you really want that dance. If the girl is tired or lazy, she might not give a very good dance. When I do it, it is usually because she is stunning (appearance-wise) or unique in some way--and I take the chance. But, the odds of quality are not good, IMO.
Comments made by Jerry75