My wardrobe has also transitioned! When I came out as trans to myself, I started to buy more emo clothes as they seemed more gender-neutral to me - skinny jeans, converse, stripy jumpers etc. A lot of black! Then, there was the AWFUL early transition wardrobe, which basically consisted of some too-big men's jeans, too-small boy's jeans, and a few t shirts in the wrong sizes too! I just had no idea what size to buy, was too afraid to try them on, and also made the mistake of buying clothes simply because they were male clothes, not because they looked good on me or I even liked them....
So, my tips are these:
1) Think about what you want to look like. What image do you want to convey - e.g. businesslike, fashionable, to fit into a particular social group? What fashions do you like?
2)Look at other guys with your height and build and see what stuff suits them and what doesn't!
3) Look around the shops. You'll soon get to know which ones have clothes that will fit you and which ones don't. For example, I avoid Topman like the plague as I'm short and stocky, and most guys going in there are tall and skinny. Also, think about the market of their clothes - e.g. M&S are generally marketed towards older men, so the cut of their clothes is always rather old-fashioned.
4) Get some well-fitting clothes as the basis of your wardrobe, and work round that. Generally, jeans are harder to get fitting right, so if you find a good pair, get 2 of them! Make sure everything is in a colour that suits you too. I once bought a yellow shirt, never again!
5) Enjoy what you're wearing and wear it with confidence! It will help you pass so much better.
Good luck, and sorry for the essay, but hope it helps!
Harry x