The most important aspect to airdrops is just reading and following all of the instructions.  Make sure you sign up early, perform any and all specific tasks that are required for the air drop and make sure you have a way for them to get your coins to you.  The airdrops that I have been a part of, are coins with their own QT wallets and you have to send them your address to be receive the coins.  Are you having an issue with a particular coin that you think you should have been airdropped?  If so, post it and maybe we can help you figure out what is going on.