How we can make sure that the urine has completely passed out?

Some times when I check after urination and cleaning a small drop of urine comes out of my penis. It is not happening all times. If the urine comes like this after wudu will this affect my salath? Since I am sure that this is not happening all times, What I must do in this case. Presently I am keeping a piece of paper in my underwear after cleaning and I used to take wudu after a small interval. Before taking wudu I use to remove the paper and put a new one. Is it allowed. Also in normal cases this method is ok. But while travelling I find it more difficult to manage this problem. Since Allah Taala doesn't accept the prayers with najaz, please provide me some advice to face this problem. Jazakallahu Hairan