Also, don't try to reach that last couple inches away from you.

If you're having trouble with V's on the fold line--you have to find the straight of grain before cutting. Match up the selvage edge as straight as possible until the fabric drapes without folds or tear an end off and match that. It differs depending on the fabric but you can tell when it is finally true. It won't poof up at the fold when you have it on grain. Some people even have to purposely pull on the diagonals to stretch the fabric back into true if it has been stretched on the bolt or over-agitated in the washer. Backing fabric is especially easy to stretch out of shape since it is so large and usually a thinner thread count but it can be stretched back into shape as well.

Keep your little finger off the ruler and on the matt and it helps anchor the ruler.