Non-triathlete distance swimmer here (really don't like swimming in a crowd). If you're a 'sinker' (yeah, me too - many athletes are) learn a sidestroke. I made one up (basically New Paradigm crossed with drownproofing). You can glide with your face submerged, come up a bit as you get power from the down-side arm. Major feature in open water is you can put your back to the spray coming off the waves. Also, if you're practicing in fresh water, expect a switch to salt to change your buoyancy - and mess up your stroke, so if the race is going to be in salt, try to practice in salt at least some.