Oh I fully expect to F this up the first go around, but that's ok, that's part of the fun and enjoyment - the process.
I'm worried about the edges around the window gaskets, like you I hate seeing sloppy work
For the edges and underneath the gaskets use a strip vinyl to practice.
It is a good idea if you invite 4 friends for the roof to hold up the vinyl.
Then you can concentrate on applying it.
Makes things much easier if you do it the first time.
Clean the roof with window cleaner first.If you have tree sap,clay bar it.
Get from a local painter a dust cloth(sticky cloth that binds dust.This is the last step before applying.
I hate dust particles showing through the vinyl,figured this is the best way to prevent most of it.
Get a squeegee with cloth protection,that minimizes the scratching of the vinyl.