I may go against the grain here, but my suggestion is buy as little as you need at first, and set a real budget (you will have other bills to worry about in transition), though that depends on what you need for work etc. You body will be changing, and also how you express yourself stylistically will as well. IDK if you have sense of what works for you or not yet, from knowing your body type and what works for it, to knowing how colour works for you. I had a decent notion of all that as an artist, but I spent a ton on things that I later looked at and asked, what was I THINKING? Also, my body changed enough that what I bought earlier I had to give away -- I lost a lot of bulk and a shoe size. I gave all my old clothes to charities, or threw them out.
I'd buy a few classic, dependable basics at first, wardrobe staples (think LBD, black skirt, black pants, jeans, a few versatile tops, etc) mixed with things you use to experiment with style and daily causal. Build from that as you figure it out. Don't buy a lot of jeans and shoes -- it's tempting but your bod changes and you begin to know what works in shoes and what doesn't Don't be afraid to borrow to test something, or to buy and return. Believe me, it's expected.
I also suggest that you don't buy a lot, but buy quality once you know what you want. It doesn't mean spending a lot, it just means know what the material is and how it's sewn. There are good LBDs and bad LBDs.
One useful book I saw was "Color Me Confident" which is a sort of makeover book that picks up from the 1970s "Color Me Beautiful." It helps you figure out some what you really want and need, and it has some tips about how to deal with one body shape or another. It also deals with face shape and hair style etc. It's meant to help women express who they are and figure out what's you. I am old enough to remember the earlier book (and gatherings of women I knew who passed it around and scrutinized each other by it), which was pretty basic. This is a nice start for any age and any background. I don't think the makeup section was that helpful, but there are lots of other sources out there for that.