Booties - get the ones that have a high ankle. Because if you buy the type of fins that require wearing booties with them, the strap will not rub against the back of your ankle like they would if you use a low cut bootie. Make sure the bootie are thick (and high cut) and made for walking on rocks. Because if you do dives and have to walk on rocky shores you will be glad you have these.
Mine are 5mm and high cut. I dive in tropical watet.
Mask-
Clear or Black outlining (plastic part): The black ones are black because it helps reduce glare. The clear ones do not. I've always dove with the black outline type masks so I cannot say whether it's actual better than the clear.
Then there are masks that have, like, side lenses, which offer a wider field of view. I don't have this one but if I was to turn hack the hands of time and repurchase my gear I would get this one.
Snorkel
Buy the one where the water doesn't splash in from the top. (the opening is more narrow). And you should be able to blow water out of it easily while keeping your head in the water (while on surface). I have a foldable one but I've never actually had to fold it to carry it around.
Fins...
You have different types: The open heeled ones (you need to wear booties with these) the closed heel kinds (you don't need booties, just slide your bare feet in) some come with a strap that you fasten/buckle, and some are spring-loaded straps (you don't fasten these you just pull the strap over the back of your ankle)
For fins I guess it's just preference. There's this one shop, they have all of their divers wearing the split fins (atomic aquatic) and they're like $200 pair of fins and they swear by it.
Mine are not split fins, (Cressi Frog) and they're fine for me. I've done close to 40 dives with them. It did take a couple of dives to break them in, though. I would say maybe the first 4 or 5. Because it felt harder to kick at first.
I've worn scuba pro fins, the spring-loaded kinds and I REALLY liked those. Because I don't have to buckle (fasten) my fins on, you just stick your foot in and slide the spring-loaded strap over your ankle. I dove at an aquarium, they provided the gear so I got to try these!!!
Gear bag
-different kinds...
Mesh gear bags
Gear bags that have wheels at the bottom (like luggage)
Gear bags that you can also wear as a backpack.
Gear bags with no mesh
Wetsuit
Glued/blind stitched types keep the water from seeping out.
Thickness depends on the water temp you'll be diving in. I dive in (sub) tropical water and use a 3mm full and I have a 2mm shorty. I still use my full suit on 81 degree water temps. But when it's in the upper 80's I use my shorty.
This is just into on the different types of gear to help you decide. When buying my gear I was doing alot of research of the different types
When its time for you to purchase a dive light, get the ones that you can charge in the wall outlet (or even car charger kinds). Batteries are expensive and you don't want the ones that you have to buy batteries for.