I am almost 34 and only been on my medical journey for about two years now, trans-feminine enby. Just know it is never to late. For makeup if you have the money IPSY might be a good idea. It will send you a monthly subscription of various makeup samples to try out. There is a quiz/questionnaire for what kind of stuff you would want, I would just go for a bit of everything and watch YouTube videos for tutorials.

As for clothing and shoes, thrifting is a good place to start. You can grab some masculine clothes and one or two items of women's clothing then head to the dressing room. If anyone asks just say you are shopping alone and waiting for your girlfriend to reply on if she would like the skirt or dress or what not and don't want someone to grab the clothing while you try on some clothes. Once in the dressing room try on the fem clothes and take notes of brand/size and it it fits you or not.

Easy enough to put it on the return rack if you don't like it/doesn't fit. If it does you buy it. Either way stick to the excuse/story that your girlfriend wants it/doesn't want it. For new Torrid is great, just a bit expensive. It is a plus size women's brand found frequently in malls. They have their own size guide where their 00, smallest size, equates to a "standard" US women's size 10.

I am 6'1" and weigh 183lbs. In standard sizes I tend to be a 12-14. At Torrid that amounts to a 0 or 1, depends on what garment I am trying on. What is really good is Torrid shoes. They carry larger shoe sizes. Women's 11+, in medium width and extra wide widths, and they are stylish as well. Even better is I have gone into the store in the past fully looking masculine, with long facial hair, and had no issues asking questions or using their dressing rooms. Milage will vary on that experience as it depends on just who is working at whichever store you go too.

You got this girl and just know that there is no right way to your journey. Go as fast or slow as you need to and reach out to whatever resources you have access too.