Leave no inch of his body untouched! If you feel shy about it, blindfold him. Pay attention to his reactions. If it's a place he really likes, don't spend the whole time there. Go to other places but keep coming back to that "sweet spot". That's the secret to longer tickling sessions. Alternate between feeling really good giggling tickles to laughing so hard he can barely breath tickles! I like to give no warning of what's to come and surprise attack him! Of course feet, stomachs and underarms are the most obvious tickle spots but nipples, necks, ears and behind the knees can all be ticklish too. If you want some places around his penis, try all along the crevice where his leg and groin meet. Also try the "tween". This is the area right below his balls, between his balls and well you know. From underneath, the very bottom where his butt cheeks meet can be a good place. Spots that are rarely touched will be really ticklish. People can be ticklish in an area one day and not the next. So don't rule any place out just because he doesn't laugh the first time around. Also, the more often you tickle someone the more ticklish they become. I used to only have a few sweet spots, now I'm ticklish just about everywhere!
Also, try some different ways of tickling. I'm a huge fan of tickling toys and have a whole box full of them! You can tickle with your fingers, your toes, your tongue, your hair. If you know he likes feet, besides the obvious finger tickling, try licking between his toes and up the arch of his foot, sucking on his toes while rubbing your tongue up and down them or dragging your hair between his toes. Sometimes the tops of feet can be just as ticklish as the soles, so try that too. Be creative! I still come up with new techniques all the time.
Happy Tickling!
sunfire