I don't think there's really any specific "order" to things, just do it how you see fit. I personally started out with binders, then mens (actually boys) shirts, then also pants, then boxers, but pretty much any order is a good order, as long as you're comfortable. I sort of slowly eased into it over a period of almost a year, but if you want to suddenly change everything in your wardrobe from one day to the next, I guess that's fine too. People obviously might ask what's going on though, or make comments about it. And it'd be a pretty big change to get used to, I would think.
It's great your dad is supportive. Hopefully everyone else will be as well. It sucks when people aren't.
Edit: Oops, forgot to add some other things.
As for where to buy clothes, you can get them pretty much anywhere where they have your size. You can go to a few local stores and have a look at the men's section, or kids if you're too small to fit into the men's clothes. Your other option would be online shops, but I don't use those so I can't really help you with those. There are a few specifically for ftms that carry normal clothing.
Binders. Most people recommend underworks binders from what I've seen, but I don't really have the money and use cheap eBay binders (which is not a good idea since they can be dangerous and generally don't work well). Definitely don't bind with bandages or anything of the sort.
Not quite sure with what you meant by "how to start". If it's meant as in generally transitioning, it's probably better to start slow. Over time you'll become more (or less) sure of things and should overall have a better idea of how you feel. Especially about the transition. If wearing mens clothes and passing makes you feel uncomfortable, obviously, you might not want to continue and it's easier to go back before you start hormones and surgeries and tell everyone. On the other hand, it's also something new and you might feel strange about it until you get used to it, which is why it takes time (sometimes). Of course it doesn't apply to everyone, but it's probably something to keep in mind.
Sorry about my ramblings getting this long. I'm not even sure they make sense because I'm not typing this out on a computer and reading everything ten times.
