Reddit mentions of TYR Women's Hurricane Category 1 Neoprene Wetsuit

A dozen or so open water sessions would be plenty, and even fewer if you feel completely comfortable during the first ones. You don't need to build fitness in the water. You just need to acclimate yourself to swimming in dark water with chop and practice sighting so you know where you are going.

I recommend you pick a race that is highly likely to be wetsuit legal. A wetsuit can go a long way to reducing the odds you feel open water anxiety. It's soothing to know you will float no matter what.

If your open water practice is limited, you should practice with your wetsuit several times in the pool. Your body rests higher in the water in a wetsuit so the angles of your catch and pull are different. Again, you don't have to go crazy and live in your wetsuit. You just want to be familiar with the difference a wetsuit makes on race day. If all the pools you have access to are too hot for extended wetsuit sessions, core shorts are a pretty good substitute for wetsuit training.

Swim at least one open water day in choppy water. You'll find you have to conform your stroke cadence to the waves so that you breathe as you are coming off the crest. This is easy to learn, but if race day is choppy you don't want to be doing that for the first time that day.

Complete some shorter races so you know what it's like to swim in a crowd. You will get kicked in the face on race days. Getting used to that only comes with practice.

If you were trained to use your kick for thrust with a six-beat flutter kick, I recommend you switch to a two-beat kick. Your kick should be mostly for rotation. Triathlon swimming is about saving your legs.

Good luck and congratulations on taking the first steps!