You can very tricky with your trapping hands.
You can do things like baiting him. This is basically where you get your opponent to try to execute a parry, grab, attack, or what have you, so you can effectively counter. An example of this is I have my hand up, but my left hand is centered and more forward then my right. I can move my left closer to him to cause him to try to slap my left hand down to execute an attack. I recognize his attempt, so BEFORE he makes contact on the parry of my left hand, then I move my left so his parry never makes contact while striking an opening (left or right, doesn't matter). Another example is I purposely leave an opening that I believe he'll take, so I can appropriately counter.
Fainting is more fun. This is where you throw a strike which causes him to react (block). Before he is able to complete his action, you abort the technique to execute another. An example of this is you throw a right hand backfist to his head. If he doesn't block, you follow through and hit him in the head. If he does move his left to parry, lets say, you abort the technique before he makes contact with the parry, circle your right behind the left, slapping the left parry hand down while simultaniously striking with your left.
You can utilize the slipping or dodging techniques. Basically, if you usually parry with your hands, he'll be expecting you to execute a block or parry when he strikes at your head. Instead of blocking, you slip. He was waiting to "feel" your block or make contact, when he doesn't get either result, there is lag time. During this lag time, you are striking.
Utilize the blast or "straight blast." Your action time is faster then his reaction. So when his hands are in a transition, just punch him striaght through his guard.
Utilize "the draw," "the crowd," or "the space disruption." This is where you draw your opponent into you, or crowd him so he moves away, or just outright disrupt his space so he is out of his comfort zone in relationship to you. In any of these cases, your causing your opponent to have to restablish his stance or space, causing a transitionary period. You are more able to strikehim during this period. So, If he is a defensive player especially, then you want to draw him out of his comfort zone. You can do this best throught footwork, but not just retreating back per say. You want to step off his line (triangle stepping) causing him to have to readjust his stance and body position to get back into his "comfort zone." when he is readjusting, your striking. You can also make yourself appear to your opponent as if you are further away then you are, or closer then you are, through your stance and body height; just be careful of the grion shot in the deeper stances. You can stay just a hair out of his range most of the time, causing him to have to attempt to close the gap if he likes to be closer to control you. The bottom line is, your disrupting his balance and space so you can strike him when he has to readjust his position.
You can also do "the grapple." THis isn't wrestling per say, you are just disrupting your opponents strategy by grabing his hand(s) and wrists. when he tryes to shake your grab, or use your grab against you, you let go and strike.
"Limb destructions" are great too. If your opponents hands and arms are an obstical for you when you are attacking his head, just hit his arms and hands. Limb attacks can be very painful. Attack the back of hit hand, fingers, elbows. nerves, wrists, etc.
Bottom line: there are tons of things you can do when playing with anyone! I think it would be more helpful if you could illustrate what techniques and strategies your wing chun friend is using thats giving you trouble. We may be able to better help that way.
PAUL