I do walk round palm readings. There are several good books on the subject - the one I always recommend is Johnny Fincham's "Palmistry - from apprentice to pro in 24 hours."
Once you feel comfortable doing readings (some people find it easy, others have to work a bit harder), it's not such a huge leap moving from strolling magician to strolling reader.
Have a pack of tarot too and you've got more in your arsenal than a hundred spong balls and a dozen ropes!
