My best buys have been
Tuppence and crumble star wraps, great for skin to skin with just a nappy underneath, and perfect as a warm outer layer when it and about as easy to take off when going in to the warm, and safe to use in sling and car seat (DD is now in the large size and we still use it loads).
Swaddle wrap, worth having one ready, as if you're little one needs to be swaddled it is a must have, we used swaddleme original, and swaddleme wrapsack when she was a bit bigger.
A good semi structured carrier, we have an ergo sport (I think) but had to use a newborn insert to start which was a bit of a faff, but I think ergo and Tula do a from birth carrier that doesn't need an insert, which I think would be better.
Out n about nipper, we live rurually and have a dog, it is a great off road pushchair and with car seat adaptors can be used as a travel system.
Snoozeshade, DD naps in her pushchair either on walks or in the garden, we have found this share indispensable.
Cheeky wipes system, we fully cloth nappy but even if that's not for you these wipes are brilliant, so much better at sticking to milky poop then disposable wipes, and you save a huge amount of money and the environment with them.
All the above items have been purchased second hand from either eBay or locally.