One problem that I had was switching pieces to look for. I would look at a piece- blue/yellow and search for the other, after a second or two I automatically thought that the other piece was hard to find, so I would switch to another piece-green/white and I looked for that. This might just be my personal problem, but I started say the pieces colors out loud, and that made it much quicker. I eventually grew out of this problem. Just always look for one specific piece and don't switch(under normal circumstances) because the piece can't be far.