Velox rim tape is easy and clean to use. Some riders roughen up the base of the rim first and put a coating of rim cement on before fitting the tape. I have always fitted the tape straight down on the rim without bothering with the other two operations. The only problem that can arise with using these double sided tapes is that on long descents where the brakes are used a lot, the heat generated can reduce the stickiness. This is why the "Pros" prefer their tubs fitted with rim cement.
Best wishes and be lucky. Michael Butler Huntingdon UK.