That's a good site, but here's what I do.

Cut the fiberglass to size with a slight overlap at either end (1/2" or so).

Use the masking tape shields on either side giving enough room for a 1/4" gap on either side of the tape.

Apply a brushing of 30 minute (or longer) epoxy with an acid brush.

Lay the glass tape on that.

From the center brush on more epoxy to wet it out. As you get near either end snip the fiberglass cloth off (this prevents it from "walking" off target as cutting to size first can).

Remove the masking tape.

Lay a piece of waxed paper or cellophane wrap over the epoxy and smooth out the air bubbles with a credit card, business card or other spatula. Gently, you don't want to squish all the epoxy out, just the air bubbles.

Leave the covering on overnight.

Peel off the covering. No sanding required. But you will want to sand it lightly before painting or covering to remove the waxes (amine blush) from the epoxy and help the paint or covering glue to adhere well.