The reason you get wrinkles, folds, and creases is that you're not holding the banner material flat on the table through the entire taping process. The trick is to leave your long rule laying on the banner to help hold it flat and keep it from moving. Winkles and stuff happen because the banner material is not being held flat and motionless on the table top.
Step by step...
First draw a 2" line. I use a 2" wide 6' rule aligned to the edge of the banner material. I draw the l2" line on all four edges
I set the 6' rule on the banner about 1.5"-2" in. This holds the banner flat. If the banner is relatively small I'll add a few architect's
paper weights, shot filled leather bags, to hold it flat.
I put the tape on the edge of the banner and not at the 2" line.
Once I put the tape down I run an old squeegee over it such that the fabric pattern in the banner material shows in the backing on the tape.
Then I move the 6' rule to slightly inside the 2" line. Still using it to hold the banner material flat.
Remove the tape backing and fold to the 2" line using a Brayer roller in a constant black and forth motion at a slight angle to the edge.