What is your motivation for self tattooing? It's not an advisable idea. Wait until you are of age or have the money to get one by a professional
Just make sure everything is brand new, sterile and of professional standard. TBH it will cost more to get the right equipment than it would to get it done at a studio.... and if you're underage, its just a very stupid idea.
if you are doing a small 2-d tattoo without much detail you could take an x-acto knife and make a scratch of the tattoo, not that it bleeds but the dermis is showing, after your done take a paint brush and a jar of india ink and paint the scratch. wait about an hour then take a shower or bath...but it usually does not produce the best results
oh just go spend 25 bucks on a tat you cheap bastard. pay a bum to sign for ya if you arent old enough.