With thigh lift scars (or any other type of scars for that matter) the reality is that if the post-op recovery goes as expected and there are no complications, then probably 80 to 90% of it has to do with the patients skin type. Some people scar horribly, some people hardly do at all. So I don't think it's something you can control a lot.
I know most plastic surgeons say you should cut out vitamin E in the weeks before surgery and avoid it after. Some also recommend using silicone scar creams or silicone scar sheets starting a few weeks after surgery, but those things don't work for everybody.
How do you scar usually? That's probably the best prediction as to how your thigh lift scars will end up. But, avoiding them completely is not possible.