I also use the ruler with the lip on it. Its much more steady. Always use a sharp rotary blade. I find I all of a sudden I am really putting lots of pressure in cutting and then realize I need a new blade!! I try to cut what I will be needing one day and the next day start the project. More refreshed that way!! Always make sure all is lined up really good too. Watch out for that V!! Alex taught me to make sure to take your finger and press along that bottom fold really good before starting a cut, it seems to work for me. And check for the V every so often!
Keep it rocking,