Purchase some decent swim goggles. They will give you vision beneath the surface of the water. If you want you can buy jammers or a speedo, they’ll greatly reduce drag. It does feel good cruising in spandex, but they’re not necessary. Make sure to stay hydrated and stretch before you start.
Proper Swim Technique
I am going to assume you are in a lap pool with lanes and a T at both ends of the lane. As you begin swimming keep your head down looking at the floor of the pool. Once you see that T quickly touch the wall and kick off down the lane again. We will talk about flip turns later. Focus on keeping your head down and taking a breath about every 3-5 strokes. When you take a breath, take it from the side and keep about half of you head in the water. When using your arms to pull, rotate your shoulders and think about taking long strokes and pulling the water back. Be sure to maintain a steady kick. Your legs use up the most oxygen in your body so over kicking will exhaust you faster. Now, when you see that T again try to do a flip turn. Once you come over the T take one stroke then follow your hand down into a somersault then kick off the wall with the balls of your feet. Practice flipping at the right time by going into the wall slowly. Remember you should only be kicking off the wall with the balls of your feet.
Now, just swimming a number of laps is not an ideal workout. Swim workouts are broken up into yards (or meters) with 25 yards being one lap. Most swim workouts will include 4 main strokes: freestyle, butterfly, backstroke, and breaststroke. I won't expect you to learn these, but if you eventually do or already know them i would recommend searching on the Internet for workouts. Otherwise, start with this basic workout:
Warm up: 2x200 -easy pace focus on long strokes
Main Set: 10x50 -fast paced with quicker strokes
6x75 -after the first 75 do 20 push ups/after the second do 35 crunches/ after the third do 15 frog jumps (then repeat for the 4th 5th and 6th 75)
200 -slow paced, breath every 7 strokes( if you cant breath every 5)
2x100 -fast paced , build speed every 25 yards (by the end of the 100 yards you should be going all out)
Cool down: 250 -easy pace
This is a 2,000 yard workout. you can adjust it to your level, and build off of it once you get better. be sure to eat a nice big meal filled with carbohydrates after your workout and to drink plenty of water. Bananas will also help reduce the possibility of cramps. I hope you can find a way to use swimming as a form of exercise because the benefits are awesome.