For Gawds sake check you aren't pinching someone elses patch.

There can be quite firm etiquette in some places as to who has the right to play where and when and woe betide you if you get it wrong.

If it's spot that's commonly busked ask someone or hang around to see if you can see any sort of a system in play.

Oh, and always put some loose change in your hat or case or whatever before you start so nobody has to be the first to contribute.

Nude would be cool too.