For years my favorite technique was Tai O'toshi, and as a result when I started to make the switch to Uchi Mata I did it by making my back step to the outside, and attacking the near leg. I had seen Yamashita do it way many times, and I figured I couldn't do much better than to copy him.
Now I am 20 years older, and a lot more efficient so I have changed my approach dramatically. I start by pulling Uke into a circle with my collar/lapel hand and my back step is to the center as deep a possible. My guide leg is pretty much straight up the middle.
I get it in randori far more often than the old way, with far less effort.
I hope this helps. Good Luck.
-Russ (The Judo Guy)
The JudoGi Store www.judogis.com
May your way be gentle.