I went from upright straight to the Vendetta about five years ago, and had no idea what I was doing. My first rides were on arrow-straight, super-lightly traveled roads, where I would occasionally practice gentle swerves left and right--nothing so advanced as figure-8's yet. Having rear-view mirrors helps to keep an eye on traffic. Like Brad said, clipless pedals do help with control, even though the idea of being clipped in seemed scary back then. I eventually graduated to making large turns in an empty parking lot, first one direction, then another. Then figure-8's. The trick for me was to remind myself that there was no rush. If I learned it all in a week, great. If it took a month, or even six months, so be it. Heck, if it took a whole year, but I was noticing improvement along the way, then fine. As it turned out, it took me about a 1000 miles before I didn't have to think much about what I was doing. Now, several years later, it is as natural as riding an upright, and a whole lot more fun and comfortable.
One thing about having a death-grip on the bars: mine was so bad, so tight, that I tore a tendon in my right elbow, sidelining me for seven months while I did a lot of PT. While down I sought advice and got this gem from Robert at Cruzbike: grip the bars as if holding ripe bananas. He was absolutely right. Once I was rolling again, I realized that I had been unnecessarily fighting my legs with my arms rather than smoothing out my pedal stroke and using my arms only as a mild stabilizing input. Now, even when motoring along under full steam, my grip is light and my arms never tire, no matter the distance. The only time my arms really come into play is when sprinting or climbing up a short, steep pitch, similar to getting out of the saddle on an upright.
Enjoy the journey. It's totally worth it.
