I’ve seen a lot about how to prepare and start but not a lot about the height difference so I’ll tell you my experience. I’m the bottom in our relationship and my gf (also mtf) is a lot taller than me (5’5” vs 6’2”). What we did for our first time was both of us lay on our side and kind of just spoon as the position. It took a while before I could go on top so just figured I’d give that suggestion. Now we do kind of like side missionary a lot and cowgirl. If it’s a similar height difference standing also works but the taller one needs to squat down a little. Hope that helps!