Dude, This is what i do.

Put tape around the perimeter and, middle and front. Before u apply it to your head for positioning, spray the tape thats on the piece with some alcohol, just a little, which gives u extra time to position the piece if u need to. Once its positioned and down press gently around the edges and the hairline. After that use a cotton bud ( Q tip) to get some glue on it, and touch up the places in front u think need it.

YOur done. I have been wearing for many years now, and i must say this part can be challenging still, especially if the hair is quite long.U can use clips to hold the hair in place which will make it easier to see what your doing.

Good luck

Sam