here's a tip
when you perform you should do a false flash or just something like that...in school i was doing 3 card monte and the first one i always do normal but when they got it right they were so happy just to catch me and then when i did the same "motion" the second time, but using the sleight, they went crazy and they were like i saw you do it exactly the same as before what the f@*#
Then seeing that it worked i tried it again...
i was doing some coin magic and i sleeved the coin and made it disappear and they were really impressed and then i did a really bad retention vanish making it obvious that it was in the my other hand and one kid said "oh i saw that, u just put it in the other hand" then i sleeved showed one hand empty, "they said open ur other hand" then i did and they went crazy they were like "what i saw that it was in the other hand"
you don't have to i just find it works well for hecklers or most people will probably be saying in their mind "oh its in the other hand whatever i won't say anything"