Along with some of the suggestions above, I find that if I stand up while cutting my fabric, particularly those long width of fabric cuts, I am more accurate. It seems so simple but standing gives you better leverage. When I get lax and try to just sit and cut, there is movement of the fabric or the ruler and inaccurate cuts. Using the weight, bag of rocks
, is a good idea too. Made me think of Donna Jordan using the work out weight. Yup, it works!