I learned unclipped from spds, just riding on the centre of the shoe, then gradually started clipping in. Even now though, if it's particularly bumpy/windy, I'll unclip my back foot as I roll into the stand, just in case of the old sideways topple! Oh, and I'd recommend practicing somewhere flat and quiet, i.e. not in traffic.
I learned unclipped from spds, just riding on the centre of the shoe, then gradually started clipping in. Even now though, if it's particularly bumpy/windy, I'll unclip my back foot as I roll into the stand, just in case of the old sideways topple! Oh, and I'd recommend practicing somewhere flat and quiet, i.e. not in traffic.