sounds like my first time. Back when I used tape, I had horrible times detaching and reattaching my unit. The tape was hard to get off the unit, and after cleaning it wouldn't stick to the lace. And I had residue in the lace after mirror slide. I finally got the whole procedure down to about 45 minutes.

First I put a bandana around my head, resting just below where my attach was. Next, I applied 99% alcohol on the unit where the tape is from a small squirt bottle that I set up just for that purpose; use a liberal amount, squish it in good, and the unit will detach from the tape rather easily with little to no residue on the lace. The 99% neutralizes the adhesive, but will not clean as effectively as other solvents. Anyway, the tape should stay on your head. If it doesn't, it will peel off with more 99% from the lace side of the unit. Once the 99% has evaped enough, you can begin the mirror slide. If your attachment is only 7 days or less, there should be minimal residue to slide off. If you have a lot of breakdown, switch tapes. Supertape is good, never tried Walker, but heard it's good too.

Now to get the tape off your head, use 99% or just peel it off. Getting the residue off your head needs something to dissolve the glue, like citrus or de-solve-it, or duct tape(!) as described in this thread. After cleaning yourself and your unit, you are ready to reattach. I always put tape on my head first rather than the unit because I could never the tape to properly stick to the lace well. Lace is not very receptive to tape in my experience, and I got tired of hassling with it and put tape on my head instead. However you apply the tape, when you reattach, spritz some 99% on either the tape or the unit to allow you time to adjust the unit to proper position. The 99% will evaporate, and you will have a good bond. For a glue front, after attaching the unit with tape, before flipping up the front mark the hairline with a pencil, comb, or anything to leave a pattern so as to guide you in glue application. Flip up the front and apply the glue according to the pattern. Once you get basic de/reattach down, you can personalize your routine. Remember, the longer the attachment, the bigger the mess to clean.

This is/was my routine, and should help guide you to find what works for you. Other wearers will have their tips, also, allowing you to pick and choose what works.