It's a lot of work. I had a week of rain interfere with mine as I can only devote an hour or two a day to it, thankfully I could keep the whole thing covered.
Check the wood under it, my small repair turned in to the whole roof when over half the wood showed rot and water damage/stains.
Seal joints as best you can, I did two strips of caulk then taped the seam. (I prefer function over form, not letting water get in, and if it does, limit how far.)
In my vent cut-outs, the insulation and both layers (ceiling and roof) were exposed, which means if any leaks make it under the vent, both could wick the water in... So I taped those as well, so should water get in, it will fall to the floor and not be absorbed.
