1. What are embellishments?
Embellishments are little flourishes that the follower does to decorate the steps that the leader gives her. In tango followers are always standing on one leg or the other, never both. The leg that the follower is standing on belongs to the leader. He put her there and it is her job to stay on it for as long as he wants her there. However, the free leg belongs to the follower and she can do whatever she wants with it as long as she is ready to step again when the leader proposes.
I like to put embellishments in 2 main categories: Stationary (ones are done during a pause) and Moving (ones that are done while moving though a step to accentuate the half beat). You could classify them further into subcategories of Rhythmic embellishments (staccato and sharp, good for faster rhythmic music) and Lyrical embellishments (slower and more flowing, good for slow dramatic music). There is perhaps another category of embellishment which some women are very good at, which is embellishments with the body (small movements of the chest, shoulder, etc.) instead of the feet and legs. These cannot be easily seen and are done just for the leader.
2. Why do embellishments?
Embellishments are good for ladies for many different reasons. First and most obvious is that embellishments are fun and look pretty. And everyone knows that ladies like to look pretty! They are also a way for the followers to express their musicality. A good follower never does an embellishment automatically but does one because she is inspired by the music and the man she is dancing with. If embellishments are done musically the leader can feel it in the follower's body and it makes a big difference the dance. Learning to do embellishments will help followers learn to hear the music. Learning them also helps the follower develop strong and fast legs and feet. If you can add an embellishment in the middle of a step still keep your timing and balance, then think of how easy that step will be for you if you don't do an embellishment!
3. How to do embellishments
When doing an embellishment always put energy down the entire leg all the ways to the tips of the toes. Often you will see followers doing embellishments with a 'loose leg' - i.e. the knee is bent when it should be straight, or the leg is energized but the foot is limp and un-poised. For stationary embellishments that are to be done with the foot touching the floor make sure you put energy down into the floor - which means light pressure. Don't let your foot dangle 1/2 an inch off the floor. Sometimes the foot doing the embellishment comes off the floor because the hip of the free leg is lifted. This will put you off balance as well as lift your foot, as the pelvis is heavy and a misalignment here will ruin your whole axis. Relax into your standing leg, settle your weight down though the hip over the standing leg and the hip over the free leg will naturally drop slightly. This will allow you to put your free foot down to the ground and make the embellishment happen there.
4. How NOT to do embellishments
One thing I can say is never do an embellisment half-heartedly or timidly. Following can become a too safe a place sometimes. When we just follow the leader we let him choreograph the entire dance and are afraid to put anything of ourselves out there. Don't be afraid - go for it. Do an embellishment and be proud of it, even if it doesn't come out perfectly. The only type of embellishment I think looks bad is the one that is tentative and hesitating. We ladies don't allow the men to be hesitating and unsure in their lead; don't be unsure in your dance either. Anything done with confidence and with the music is going to look great. It doesn't matter if your embellishments are imperfect -- do them with personality and gusto!
5. How do I find the time to do an embellishment?
Women in classes will often ask me how to find the time to do a particular embellishment, and there is one answer for this: PRACTICE. You have to try an embellishment many times before you get it right and are able to fit it smoothly into a space in the dance. First, practice it on your own. Hundreds of times. While listening to music. Then, try it when you are dancing with a guy. Do it with someone you feel comfortable with (you could even mention to him that you are trying something new). The first dozen times you do an embellishment it will probably be a bit bumpy. You may even mess up the next step or trip yourself - it's OK! When guys try new steps that they have learned on us it may be a little rough at first. We have to accept that we may make mistakes at first when trying an embellishment as well. Making mistakes is how we learn.
That said, once you become good at an embellishment it should no longer disrupt the lead in any way. You must always be ready to cut an embellishment short, even if you weren't 'finished' and move again. How do you tell when the leader is going to move again after a pause? You will be able to feel that the next step coming if you pay attention to the bodies of good leaders. Usually he will flex his knee slightly (or a lot) in preparation for the next step, or start to move his center forward. You should prepare with him, stop embellishing, and match his movement.
Sometimes leaders will wait for you to finish your embellishment before stepping again. Don't be greedy and bake a whole batch of cookies. Taking more than a couple of beats to do an embellishment looks fake and baroque and doesn't not flow with the music. Not to mention, you are stopping in the line of dance and may be causing a traffic jam behind you!
On the note of floor-craft, it is not only the leaders job to be aware of the surrounding space. The follower must also pay attention and never pick her feet high off the floor unless she is sure she is not going to stab anyone with her stilettos.