From hard experience, start with a first quality top, If you get the bargain top(or allready have it)seek professional help, and be prepared for poor results. The cheaper the top the worse it will fit& look.
Once you have a first rate top your life will be much simpler, it will go on easily.Start at the backand mount it to the body as before, then work your way to the front.Replace any padding that is falling off the bows(it prevents chaffing)
I like to use seatbelt matterial for the top webs, it is stronger than heck, and lasts forever.
Use a small nail & lighter to snell the screw holes into the material. I have found 3M weatherstrip adhesive(black) to be the hot trick for doing the front bow.Use it as a contact adhesive(a little on both surfaces partialy dried)
Get the canvas fairly tight,and then set the bows onto the windshield & latch it down. This glue is messy but forgiving, Goo gone will get it off of places you didnt intend to have it.Strech the top as much as you can, then finish up the gluing around the front bow. lastly poprivet the strip that holds the weather seal to the top.
The tr7 top is even simpler, but it is best to have 2 people for the job in either case
Good luck!!
MD(mad dog)