For a lot of people making that initial jump from pool to Open water is a massive step so here are a few pointers that may be useful when first venturing out:

If very nervous of the water, build up gradually. You don’t need to get in and swim crawl straight away.

The cold water when your first hit it can leave you quite breathless. You are best being ready to swim head up Breastroke.

Try to let the water warm up a bit before you try out OW for the first time. Just swimming outside is challenging enough without adding extra obstacles to overcome.

If really nervous maybe don’t even start with swimming. Maybe try walking into the water, do some bouncing up and down whilst water is at chest deep. (It would be useful to try other OW based activities such as paddle boarding or playing with the kids in the surf on holiday to build up confidence.

Safety is obviously paramount. If in doubt don’t get in. If feasible, go to an organised session or a patrolled venue. Swim with a group or at the very least a partner. (Maybe consider having a session with an OW swim coach.)

Wear a brightly coloured cap and a swim buoy. This is not a life preserver but does provide some buoyancy. It is designed to make you more visible in the water. (They are usually a requirement if swimming without a wetsuit.)

When swimming there is no issue with swimming breastroke or crawl, or even a mix of both. In events either is acceptable (In an event if in trouble you are meant to turn onto your back so backstroke is out.) Therefore before any event experiment with both and develop a strategy that works best for you.

To help you here is a discussion of the two strokes when used in OW.

FRONT CRAWL is faster (if swam properly). Your main means of propulsion is from your upper body so it should preserve your legs for the bike and run. Underwater you take up less space so it is easier to use when swimming in a group. The main drawbacks are that it is difficult to sight and when your face is in the water visibility is not good. Also because of things like the cold and being nervous it is possible that you may find breathing a bit more difficult.

BREASTROKE, for many people, is an easier stroke to do. This is mainly because you are facing forward and the stroke more naturally supports the breathing pattern. For these reasons you may prefer it when swimming OW in that it is far easier to sight and breathe. It’s drawbacks are that it requires much more effort from your legs and so is tiring for the bike and run. Also, because of the wider leg kick you take up more space and possibly more like to catch somebody else that is swimming.