Are you looking for a western bit or an english bit? You can
neck rein in any bit, you shouldn't direct rein in curb bits. You can neck rein in your snaffle. If you plan on direct reining (two hands) do not use a curb, these signals aren't clear.
Now first things first, by yourself a set of rainbow reins, they're super pretty and will remind you to keep your reins even and you can see when you're holding too tight. These are a good investment until you have the 'feel' for where to hold your reins.
Now, if you want a softer bit for your horse here are some options.
If you ever plan on direct reining I suggest using a french or a ball snaffle, these have 2 joints which reduces the nutcracker effect when you have hard hands. Do not use a double jointed one that has a thin flat piece in the middle, those little flat pieces are pressure points. My favorite double jointed snaffle is a a myler (picture below) it has tongue relief, and individually rotating sides. This produces very
clear signals for your horse. It only effects the side of the mouth you apply pressure too. I also suggest a full cheek if you horse doesn't have a habit of rubbing their head on you or other things to get caught on. Full cheeks with bit keepers help hold the bit in the correct position in the horse's mouth, encouraging them to hold their head correctly, as well as preventing the bit from being pulled through the horse's mouth if you have hard hands.
Now if you plan on only
ever neck reining, not direct reining, and still want a mild bit I suggest a Sweetwater curb bit like the picture below. This bit has a curb strap, thus has some leverage, but because of the short shanks and the well sized purchases this bit has very mild leverage. The purchase it the part from the mouthpiece of the bit up to where the headstall attaches, the shanks are from the mouthpiece down to where the reins attach. The longer the purchase and the shorter the shanks, the milder the bit. A bit with long shanks but with a long purchase is still a mild bit. Also, because the bit is made with a mullen mouth it provides tongue relief without the possible pinch of a port. This bit is as soft as they come, for a well mannered responsive horse who neck reins. Do not direct rein in this, pulling one rein will engage both sides of the bit causing the horse to stop or become confused.
I recommend using as soft a bit as possible until you develop softer hands. But really you should get yourself a set of rainbow reins (I love them!). If you can I also suggest getting an educated friend or a trainer help you work on your own rein handling skills.
Good luck I hope this was informative!