I’m a little late (where does the time go?), but here’s my two cents.
I don’t think a bike with a freewheel can be ridden with the same precision as that of an artistic bike. I’ve never ridden an artistic bike (and my riding isn’t very artistic) but I’ll try to give you an idea of what works for me. John is obviously the expert to take advice from, but it seems like there is a steering difference between a freewheel and a locked hub, since you don’t have the benefit of being able to weight the pedals for balance assistance as with a unicycle. This limits the turning radius quite a bit (at least for me). I can’t turn tighter than 4 or 5 meters. Like anything that takes a long time to learn (and I’m still learning) it’s not easy to explain. Feel free to ask questions if something doesn’t make sense.
Basically, I use body lean (including moving around on the seat) as a course adjustment, handlebar/frame (side-to-side) movement as a medium adjustment, and handlebar turning as a fine adjustment. Even without a front fork, bar turning provides enough body twist to make minor corrections. Starting into a turn, I turn the bars and lean the frame slightly in the opposite direction of the turn. As with any counter-steering, this causes my body to lean into the turn. I then turn the bars in the direction of the lean and also lean the frame into the turn. Leaning the frame consists of pushing sideways on the bars as opposed to turning them. This provides the affect of twisting, which John mentioned. The correct combination of body and frame lean, along with handlebar turning will keep the bike in a controlled turn.
To straighten out of the turn, reverse the process. Turn the bars and lean the frame further into the turn. Centrifugal force causes your body weight to lean to the outside, starting the process of straightening up. Then bring the frame back up and turn the bars back to the forward position. At any point in the turn, or while going straight, turning the bars or moving them side-to-side, will help you to fine tune the balance. The hardest part is learning to feel which way you need to correct before you need to make a major correction.
It’s very easy to over-compensate, especially when you’re not sure which input will make the desired correction. Try to start your turning practice in an area where you can ride large circles, then reduce them gradually. Since you’re comfortable with the forward and backward balance, you have the benefit of being able to learn the turning at higher speeds, which will make everything more stable and cause less difficulty with over-correcting.
Steering is easier behind the balance point, where you’re pushing the wheel instead of leading it. You might try practicing on a slight downhill if you’re comfortable with the brakes.
Low tire pressure (especially with knobby tires) causes the frame to fall sideways without turning. The same problem exists when riding on grass or other soft surfaces. High pressure road tires work best.
Seat position – I have much more steering control with the seat lower and further forward than usual. The standard theory that you should be able to almost straighten your leg while pedaling doesn’t mesh well with steering on one wheel. For me, better steering is worth the power loss.
Riding in the wind will aggravate the learning process. It takes very little wind to screw up the steering (unless you remove the forks, which I don’t recommend). If you figure out how to compensate for it, please let me know. If there is enough wind to blow the front end in a different direction than I need to steer, I either have to turn with the wind, drop the front end, or crash, since fighting the wind requires leaning in the opposite direction of the way the bike is being blown. This can lead to a quick face plant. This isn’t much of a problem without the forks, but when you have to make a surprise stop (as I experienced with a wheel seizure), it’s a big problem.
If this becomes a lasting addiction (as it has with this old man) you’ll reach a point where your riding time or distance becomes limited by loss of brake control due to hand fatigue. That will be the time to install a second brake, to be operated by the other hand. This is the most beneficial modification I have made. My max distance was limited to about 13 miles before I decided to add a second brake. My first test ride was stopped by a cop after 16 miles. The inexpensive ticket was a comical end to the ride. Riding time is now limited by butt pain/numbness (if it’s not windy, that is).
Have fun, and keep us posted on your progress.