The first responsibility - of both the leader and the follower, is to really listen to the music. Listen before you move. The more open you are to its influence, the sooner it will carry you along to its heart.
Always bring yourself back to this basic starting point.
Slow down. As you get excited, you lose it. The time to concentrate on details is in your own practice time. On the floor, it is only time to lose yourself in the moment. That calls for a certain unconcious competence.
Practice, practice, practice. Only practice will get you going smoothly. And each beginner must practice regularly alone at first to become sure of the basic movements. Moving with the music is the beginning of being able to enjoy the dance with another. The follower must be able to do her ochos, for instance, without holding on to someone or something. The leader must work out in his mind what he will lead next - and compose little combinations he likes of the figures he has learned. Fluidity will come. Keep your "frame" up at all times when you move by yourself. Act a bit - move as if you were a great dancer already. Tango isn't just about your feet, it's about all of you - spirit, mind and body.
Dance with new partners. Go dancing often for the fun and pleasure of it!
Remember it's your ‘body memory’ that is most important. The moves have to become automatic for it to work fluidly. Figures or "steps" are for your body memory, not your head. In this way, it becomes automatic and you're on your way.