Using the bathroom that agrees with your gender identification is a matter of knowing your bathrooms, common sense, and observing how busy and who has entered the bathroom. I know at the fast food restaurants, Wendies, McDonald's, Krystal, etc., that the womens bathrooms have two encloses stalls, one large one for wheelchairs which has a toilet and sink and one smaller stall. If a bunch of other women or young children have entered the bathroom, it makes no sense for me to go into the restroom and stand around with the other girls because I run the risk of not being accepted as a woman by one of the other women. When I do enter I enter the wheel chair bathroom because it affords the most privacy for everything I need to do. I leave quickly and quietly. If you are in an urban area most people are not looking too closely anyway. When I presented as a male, I usually used the stalls in the men's room and sat down to pee, because I had bashful plumbing. Walmart has a multitude of stalls and you can usually find one empty. When you are in the ladies room behave like a lady, and in the restroom behave like a man. Most of the time you will pass, if people in the store have never seen you as anything but a man or a woman in urban areas. Small rural towns everybody knows, and life depends upon how well you are accepted and if you are seen as a threat. Don't use any restrooms in places where you have had difficuties. I have used ladies restrooms in clinics, courthouses, elementary schools, middle schools, high schools, fast food places, gas and food stations, etc and never had a problem. However, no one ever sees me as anything else than a plain dressed little old lady like you see in my avatar. I am also retired and don't work so I don't have to worry about passing in the workplace. If your inner voice tells you to be careful, be careful. Remember guys act more brassy than women do, unless as a woman you can project, that I am large and in charge. But, in that case you had better not be showing two many physical male physical characteristics. You need to act like a diva and not John Wayne.
Also it helps as a trans lady if you travel with other gals who accept you. As a trans man it helps if you enter the restroom as one of the guys. If you have children then you need to behave in your appropriate gender parenting role, and be prepared for your kid to out you, by her calling out, "Dad!" Then just pretend like she does this all the time.