When trying on a pair of jeans in the dressing room you may want to do some squats or lunges to stretch the jeans a little bit because if you buy them too loose you will have to wash between every wear which may cause premature fading.
Like I have said before you need to find a tailor! Before taking them to a tailor, wash your jeans so that all the shrinkage can happen first. (Turn your jeans inside out before washing then if possible, hang to dry.) Then when at the tailor bring the shoes you think you will wear with these jeans. If you plan on having these as your "heel" jeans, then bring heels. If they will be your "flat" jeans, bring flats! I have also said this before but I will say it again: if you LOVE these jeans, buy 2: one for heels and one for flats!