You basically do the opposite of what I do. I have a hard time getting my front hairline to look good if i put tape on the lace first. I always get ripples it never lays right on my head. and I hate using alcohol to attach, I use it to take the unit off lol. I think it screws up the bond.

What i do is i put tape around the perimeter of the unit first. and i leave the front with nothing. I leave the tape backing on the tape, but the contour on the very back side of the piece i take the backing off of that one. I than throw the unit on my head, while holding the back because the back has no tape backing and is sticky. ONce I get the unit where i want it, i tack down the back contour. U can keep the hairline SLIGHTLY higher than u would like, if u need to stretch your unit a little bit. so than when the back is taped, i lift up the unit and look at myself in the mirror. I can see all the tape, so I peel off the tapes in sections, Than tack it down, lift up do the next section tack it down, till im left with the front. Than i just attached the front last. This has been working for me.