I like using hot glue gun cuz its easy to take off if you need to. Just use a hair blow dryer and remove it without any residue left over.
Oh really? you can remove it that way? I've never known that. Thanks for the info.
Also you can use model glue, it's nice, it's like a gel but it 100% transparent when it dries it also leaves no residue, unlike superglue and hot glue turns a foggy white when it dries.
Personally I would use a dab of hot glue on the bottom of the LED BEFORE applying it to your surface so you don't use too much.