This is an awesome question! So, it depends on kink but I'm going to talk about impact play starting kits, and then I'll talk about first aid.

First things first: Do not buy sex shop implements unless the sex shop specializes in BDSM. They are not made for heavy play and I have seen them break and even splinter in ways that are clear that they are poorly-made. My recommendation is to start small and practice with a smaller set of implements before working up to having any kind of big collection. If you don't have any local implement-makers or don't know if you want something custom right off the bat, Etsy is generally a great place to look, surprisingly enough! I have a simple Florentine set of floggers that I got from Etsy to replace some that I gave away and they're still in my main toolbag even now.

My starting toolkit recommendation would include:
* One leather/TPU flogger, for "core play" - the main part of your impact
* One light cloth flogger for warmup, hard hitting, and sensation play. You can also use a very light leather strap flogger, but be careful how hard you swing it because after a certain point it'll go from sensation/warmup to stingy
* One paddle, preferably some type of treated wood instead of something like acrylic. Start with a larger surface area one if you can - this will let you spread out the pain better, and avoid fully leather paddles early on just to care for it better
* If you want a little sting in your scene, look into a riding crop. If you can, just get one from some kind of supply store or anywhere that serves equestrian hobbyists. Sting takes more time to learn how to administer versus thud, so you'll want extra time training with this one!
* A kitchen-grade meat tenderizer, honestly! You don't need to use it very hard, but it can be a great tool to get the blood moving under the skin for warmup and leave some darker bruises. And yes, you can use both the smooth and pointed sides just fine.
* Rope is not my personal forte but it is sage's so they are helping with this one: STAY AWAY FROM COTTON ROPE for beginners since it can tighten unexpectedly under greater pressure. Nylon is a very simple and standard first choice. If you buy rope, you MUST MUST MUST also buy a real pair of safety shears!!!

Now onto a good first aid kit coverage. Not all of this may apply to all of your particular needs, obviously fill the needs you see as you go and your toolkit gets bigger, but this is a great little first response bag for starting out:
* Bandages, gauze, skin tape (MAKE SURE you include adhesive and first aid-related allergies in negotiations!!!)
* Some kind of saline wound wash
* Rubbing alcohol for disinfection, recommend a small bottle and maybe also a spray bottle
* Super glue or butterfly bandages, just in case, even if you don't play with sharps
* Instant ice packs
* Vitamin E oil, for aftercare skin treatment
* Water and dense, caloric/nutrient-full snacks for any blood sugar crashes or just aftercare
* Safety shears - yes, even if you don't play with rope, you should have some, but no safety shears with rope is about the deepest red flag possible!!!

If anon (or anyone) has any extra questions or wants me to expand on any of this, my DMs are always open!!