The best recommendation I can make if you are trying to convert your "Handform-only" tai chi practice to a martial one is to take it slowly and softly,which we should have no problem with, right? You would think that after years of doing the Handform, all that flowing and relaxed movement would cross over into our martial training...
In my experience, people who do mostly Handform, and then get into a bit of Pushing Hands, tend to be stiff, tense, overt strength-users intent on "winning". This is a very curious thing. Often, they will
do everything in this way, whether it's compliance-based or not, whether it's a drill or more free-flowing.
Now "softness" is a terrible term, but it's the word that has become symbolic of what tai chi practitioners are trying to achieve. There's a reason for this quality of softness. It has nothing to do with chilling out or going with the flow or magical chi energy. It has to do with the fact that "softness" is better for fighting with than "hardness". People may become confused at this point. They may say "well softness is fine for defence, but what about when you have to put someone down to stop them hurting you?" Yes, softness is also better for that. It isn't that softness is yin, and hardness is yang, or that softness is defensive and hardness offensive. Softness can be present in both attack and defence. Which is also not to say that you don't need strength. You do need some. We might rather say that
good structure is required, which in turn requires a certain amount of trained strength. People have a tendency, especially in Pushing Hands drills, to approach them as if they were in a Strongman competition: their arms are tense, their movements mechanical, their listening skills non-existent. Four Directions or Seven Stars is not the place to train strength. You should have conditioning training for that. These drills are for training sensitivity which is best discovered through slow, soft and awareful (I know that's not a word but it ought to be) movement. An old Wudang maxim is "Fine work, neatly done." So it is with martial training. Of course, we then need wilder, more intense arenas in which to test what has been taught, but the "structured" training is best done soft and slow, unless its aim is particularly geared towards pressure testing, in which case it needs to be free enough to let the learner discover for themselves if it works or not. Put another way: one drill cannot test
everything. You can't elicit dexterity, strength, spontaneity, aggression and cool-headedness from just one drill. Everything we do in the martial arts is a drill, because it happens in a controlled environment (unless you really are putting yourselves in danger) so you have to think: what is this drill for? Do it softly, and find out.