We pay dues to be in the club to pay a coach and rent pool time. We meet at a local high school. Our coach puts the workouts up on the whiteboard. They are written in a kind of code:
4 x 150 Free
8 x 75 Free Drill: 25 RA/25LA/25 Fist :20
8 x 50 Free Build :30
Kick 4 x 150 choice, Build within each 150 :30
Pull 3 x 150 breathe 3/5/3 by 100 :20
150 Easy stroke
One length of the pool (from one end to the other) is 25 yards. So 4 x 150 Free is four sets of 6 lengths, freestyle. Usually you rest for 10-20 seconds between sets. Choice means you can choose a stroke (usually not freestyle). Kick uses a kickboard, pull uses a float between your legs so that you don't kick, you just use your arms. And so on.
We don't always get all the way through a workout -- our coach purposely puts more on the board than he thinks we will get through. At about 5 until the hour we go into our cooldown set, because we need to be out of the pool so the next group can start. The "T" number is how many yards the whole workout would be.
There are Masters groups all over the country, and you can find one through their website. Ours has its signups in late summer, and I don't think we are taking any new people now. Different groups probably have different rules.
I love the group because we have a great coach and very friendly people. It gets me in the water at least once a week. I have not been good about swimming on any day but Sunday so far. I really am motivated by a group setting more than I am by a solo workout.
Let me know if you have any questions. This is the kind of geeky stuff that I don't write about because I don't think people will be interested.