I always suggest to my customers that are interested in learning about true/tensioning wheels to start with one the aren't using. There are plenty of wheels on the curbs for free in most communities on trash days.

I agree with both the suggestion to let the selling shop handle this wheel as well as that the prior to "fixing" trueness of the rim is a BIG indicator to after tensioning results. Wheels are a system in a state of balances. Not understanding this give and take of tensions WRT rim condition when no tension is present is a path to future issues. Andy