Good question, one that isn't asked enough in BJJ schools. A few tips:
Practice, practice, practice. I like to often start classes with standing handfighting as a warm-up, since it's relatively easy on the body, allows you to move, and is clearly practical. You could do 5 minutes each day with a friend before or after class, focusing on implementing your classic wrestling grips and specific goals: inside ties, drags, establishing wrist control, tracing to the wrists from upper arm grips, moving their upper body with underhooks, direction of pressure, making them step where you want, etc. You will figure much of this out by spending time in the handfight, and bringing in someone with more wrestling experience is bound to show you shortcuts or options you didn't know.
Another good starting point would be to look at what works for you on the ground, particularly on bottom. If you can stay safe, pressure, or move your opponent when gravity and friction are working against you, the principles should be sound. The efficacy of those same principles should be amplified in the stand-up, where you have less working against you to create the movement and reactions you're trying to set up. On that same token, if you find new things working for you in the stand-up handfight, there's a good chance you could also implement them on the ground. Play around with it, have fun, and it should make a world of difference in a relatively short time.
