*hugs for natasha*
Congrats on being able to start transitioning!
Some thoughts:
natashatasha wrote:Body Image: I don't look at all feminine or even androgynous.
That will change with hormones

. It would be rather unusual if you looked feminine before.
have a bit of a belly
Healthy diet, exercise? Less fat is also better because fat stores estrogen so it can work less.
and a huge arse
That should actually be beneficial for presenting as female.
my hair is just ... unmanageable
So you are just another woman with unmanageable hair

.
I have a really receding hairline too
That should stop with a testosterone blocker, too.
I don't particularly like women's clothing
Welcome to the club - me neither.
(I kinda experiment with skirts and dresses this year ... doesn't work superwell, but also not superbad.)
For me, jeans and T-shirts are perfectly fine women's clothing.
But maybe you want to experiment with traditionally female clothing at some point, to look more feminine. If you do no dare to walk into a shop and buy some, yet, you could order something online.
How to figure out what to wear I am not sure yet myself. I guess I need to read more fashion magazines or something.
Make-up ... I don't know where to start
Cheeks, to try to cover up the cheekbones. This is what looks most masculine or feminine about a face, I think.
Or anything else. It doesn't really matter where you start. Try something in front of the mirror, see how you like it, try something else.
my reticence to go out shopping plays especially strong here, even though I'd only see the checkout person once.
See if make-up can also be ordered online.
I want to start hormones this coming year, but I don't know how to start
The standard way seems to be: Check lists online which psychiatrists or therapists other trans people recommend, go to one a couple of times until ze is convinced that you are really trans, get a transfer to an endocrinologist, first get hormon blockers against the testosterone and then gradually increasing doses of estrogene and progestogen ... or some variation of this.
I've been told I should be presenting as female before I do so, which leads to the vicious 'don't want to look like a man in a dress' loop.
Well that sucks. The US recently made huge progress so that now most trans women are able to get hormones without being forced to walk around looking like men in dresses first, but Germany is far behind regarding this and apparently Australia, too.
Check what other trans people in your area recommend, if there are any therapists that give you the transfer / letter that is needed for the hormones without having to go through this.
If it is not possible, lie. Go to the psychiatrist/therapist dressed in feminine clothes and claim that you wear them most of the time.
Body Hair: ... I intend to try the talcum powder & sensitive skin razors, and for some reason I have the same reluctance to purchase these as I do for any of the feminine things. Probably has something to do with I've never used a razor before, no idea how to use them. I've always had an electric razor (which doesn't shave very well), and don't like the idea of scraping sharp pieces of metal across my skin. Added to that, I'm rather squeamish about blood, and it's not exactly a useful tool for shaving my back either, which is unfortunately hairy too.
Facial hair: You will need to get over the fear of metal scraping across your skin and shave with such a razor, the electric ones are just not good enough. And/or start getting permanent hair removal, e.g. with lasers.
Body hair: An electric razor would be good enough. Or you could use chemical means to remove the hair (that's what I do) or sugar-based ones.
Good luck with everything! *more hugs*