I used to get UTI's but don't anymore. The only thing that I can remember changing was to immediately urinate after DTD. I have been told by my GP not to wash down there with soap as it can cause issues. Plain old water is what he recommended.

By the way even though I jump straight out of bed after DTD it didn't stop me from getting pregnant 3 times last year so it will have no effect on your chances of conceiving regardless of the old wives tales about putting your feet up or bum on a pillow etc etc.