I am trying to create a routine for myself so that I can be confident with my preparations before tevilah. I've read that if a woman doesn't inspect herself before tevilah, her immersion isn't valid. I realize that it is an extreme situation that a woman doesn't examine herself at all. How much inspection is actually required of a women? How much is required in order for her to be confident that anything found after tevilah wasn't there before? The checklists in the mikvah often list the cleaning process, but doesn't systematically list the inspection process. For example, I generally keep an eye out for barriers while I'm showering and preparing myself. I also review the checklist. However, immediately before I immerse I sometimes give a only a general look and feel at my front and back because I have a tendency to get nervous and nit picky before tevilah. There is a possibility that I may not notice an area of the body (such as an armpit or part of the leg) in my final inspection before immersing. Is the inspection I describe adequate or should have a more systematic method of inspecting my body?

Thank you so much.