A fast track dancers' guide would be The Perfect Pointe Book, a comprehensive manual covering basic ballet technique. It is invaluable whether women and men in ballet get into pointe shoes or not.
If you are in beginner dance classes for adults both for exercise and your artistic needs, here are a few tips for getting the most out of your work at the barre.
If you are doing some other, non-ballet academy barre-ish workout, you may get some tips also.
First Tip - Warm Up Before Class
The barre exercises will warm you up, completely. Yet you will get much more out of the first few exercises if you can manage at least a five minute warming up time before class starts.
At the very least, two to three minutes of walking on the spot, executing large easy arm movements, will increase your heart rate a little and get your circulation going.
Stretches before class are good for simply "getting out the kinks". If you sit down all day before a dance class, or if the class is first thing in the morning, doing some barre exercise-related stretches will ease you into the class gently.
These would not be deep stretches, but more like movements to remind your body of what is about to happen.
Doing a few rotations both inwards and outwards of each ankle, and then doing a few demi plies, either with turnout or parallel, will stretch the calves out.
If you are not so flexible in the ankles, you can sit down, sitting back on your heels, and gently pull up one knee at a time, to stretch the front of the ankle joint.
Easing Out The Hip Flexors, Or Front Of The Hip Joint
This is easily done with a runner's lunge. Standing parallel, move one foot behind you about three feet, or where ever you need to place the foot to feel the stretch from the upper thigh, over the hip bone, and into the abdominal area above the extended leg.
Pull up the lowest core abdominal muscles, and allow the pelvis to relax into its neutral (no tip forward or back) position.
If you are too tight in the hip joint to get the pelvis straight, don't worry. You are just getting the alignment that you can here, with no need for heavy pressure.
Repeat on the other side.
Easing Out The Hamstrings
Most ballet studios have a lower barre. For a light hamstring stretch, place one leg on the low barre. Flex the foot and make sure the leg is straight.
Also, keep a straight back, and you are going to bend from the hips, not curving in the low back. This keeps the stretchy part in the hamstring, or back of your thigh muscle.
It doesn't matter if you hardly move at all. You can do a deeper stretch in the break before center work when you are well warmed up.
Side Bends Lengthen the Large Quadratus Lumborum, Or Spinal Support Muscles
Standing with the feet apart, comfortably, reach up with the right arm, keeping the shoulders and neck relaxed, and bend toward your left.
Get a long pulled out stretch, keeping the left side of your torso lengthened.
Repeat other side.
The Turnout Muscles Need Stretching Too
The easiest way to do a brief low pressure stretch out of the rotator muscles is to sit on a chair, and bring up one leg, bent, with your foot resting above the opposite knee.
You can hold the bent knee up with your hand if you feel ANY strain in the knee joint. This is not about having the bent knee level like a table top, or stretching in the hip socket area.
Now you will bend forward, back straight, and you will feel a stretch in the back of the pelvis, and around the side of the hip.
Use very gentle pressure, just to alert your body that ballet class is about to start.
The "Swan Lake" Stretch
This stretch will give you a nice pull across the chest. Stand with your back to the barre, and reach behind you with both arms, grasping the barre.
Then lean away, not arching very much, but stretching out the arms and you will feel a delicious elastic feeling at some point, in this small movement.
Muscle stretching exercises done before class are very gentle. They are part of your warm up. Deeper stretches can be later in the class, or afterwards.
The Perfect Pointe Book shows you all the details of ballet barre routines for posture, turn out and gaining foot strength. I highly recommend it if you're in beginner dance classes for adults.