Yes, elevate the handle slightly as you work around an outside curve.
The best tricks I have found for minimizing wobble are to use shorter passes on the stone, and use two hands when working - one grips the handle and the other uses fingertips applying light pressure right where the edge is making contact.
The website below has video content, much of which is not specific to the sharpening block I make. The first video in particular covers a lot of basics including mechanics.
Controlling and limiting the amount of rolling is the biggest challenge of freehand - a small amount is inevitable, too much will degrade your results.