Gifts/Giveaways

I sell Color Street Nails, when people purchase nails I usually send a few extra goodies with the nails or I will advertise a purchase this weekend will get a free set or something like that. Are all my additional goodies that I send as little gifts like facial masks, nail files, lotions, etc considered a business supply or advertising expense? Also, all the sets that I purchase are not technically considered inventory because I could be giving them away so do I count those as an inventory or just supplies? I've also seen where if I don't sell a huge amount then I should use the cash method of accounting and just put my inventory under supplies?