If you plan to race using a wetsuit, it s a good idea to use one in practice. Sight-breathe one to two times per length to check how straight you are swimming.
Many people swim with an uneven stroke that pulls to one side.
This can be disastrous to a successful open water swim. 25 right arm swim breathing to the left. Count strokes per length. Try to take the fewest number of strokes possible on the second 50 by maintaining balance and a streamlined body. Start with fast but relaxed 50s.