Firstly, remember, it doesn't have to be all or nothing & you don't have to get lots of the same nappy. It's good to try a few different types & find out what you like.
You'll need about 20 nappies to do it permanently but you can build that up over time.
It's worth seeing whether your local council offer any incentive schemes & also if there are any nappy libraries near you. I don't use Facebook but I've seen people say that there is a good nappy library page that shows the location & contact details for lots of libraries around the country.
In terms of nappy types, we've used loads and over time have probably built up to 40-50 in total. A nappy for all occasions!
Initially, a 2 part nappy is better for containment especially of breastfed poo! You'll be changing them so often to begin with that you don't need to worry too much about absorbency so some kind of microfibre fabric would be fine. However, as they keep them on for longer, you might find fabrics such as bamboo better although they can take a long time to dry - we are coming into summer & if you can tumble when it's wet, the drying time is not an issue. In that case, it might be worth looking at the size 1 Lollipop bamboo which we thought were brilliant. If baby is tiny, you could look at the bamboozle size 1. The size 2 is sold as a birth-to-potty for normal sized babies so the size 1 is ideal for premature or small twins.
As they get older, pocket nappies or all-in-ones are the way to go to make things easier & to get a much better selection of colours! Our favourites have been Bum Genius & Baba+Boo. Overall, the Baba+Boo has proven to be the most durable (because of the popper fastening) although both types have easily lasted 2 babies.
In terms of accessories, definitely get a couple of lidded nappy buckets & use flushable paper liners to keep the worst off. Also, it's worth getting some washable wipes which will also save a small fortune & just get thrown in the nappy bucket with the nappies.
I can't do links because I'm new to this forum. I know the nappy lady has a good reputation. However, if you google hunnybums, we can't recommend them enough. Lucy has been very helpful over the years. She also does a trial pack with some form of guaranteed buy back although she didn't when we were getting up & running but that might be worth looking at if you haven't got a nappy library near you. She certainly take time to help you through the 'minefield' & she also does 'Skype demos' if you'd like to chat face-to-face.
HTH but just ask if you've got any more questions.