Rycote Stickies 100

I use this product to hide lavalier mics on film productions and I can warmly recommend it to anyone who hasn't tried them yet.
They might seem a bit pricey but Rycote's Stickies are very reliable and can save you a lot of time and potential trouble.

The only actual con that I can think of is that sometimes (and by that I truly mean rarely) some of the stickers get stuck onto the protective paper within the package so you tend to lose a few here and there but it's probably a matter of handling in transport. Anyways, there's a lesson there so try and give them some space when storing them and don't have them pressed against heavy objects.