There was a discussion here a couple weeks ago about whether or not you make sure your fabric is on the straight of grain before you start cutting.
Some said they tear their fabric to get it on straight of grain. Some said they pull a thread to get it on straight of grain. Some people said they never pay any attention to straight of grain. Tearing the fabric can sometimes pull the edges funny and ruin an inch or two or the torn edge.
I always pull a thread to get a straight of grain before I start cutting. My mom taught me how to pull a thread when I started sewing many, many years ago.
Someone asked if I could do a tutorial on how to pull a thread.
Your first step is to determine where to start pulling. Look for how the threads are raveling off of the end of the fabric and start in the area where the threads are at the lowest and there are threads raveling away from this point. This may be at one end of the fabric, or it may be in the middle someplace, depending on how the fabric was cut.
Start by pulling the thread at this lowest point very gently, gathering up the fabric to either side of the thread you are pulling. Pull the thread only a little at first, maybe an inch or two. (If you are starting on the end of the fabric, you will be pulling the thread only one way.) As you gather up the fabric, very gently work that gathering out along the length of the fabric. Then pull the thread a little more and keep working the gathers out, along the length of the fabric.
You will see a line forming, where you are pulling the thread. On some fabrics this line is easy to see and on some fabrics it is harder to see. Sometimes it may be easier to see on the back of the fabric than it is on the front.
Keep pulling, gathering, and working the gathering out until you have the line all the way across the fabric. Once you have the pulled thread line all the way across the fabric, line your ruler up on the line and cut with your rotary cutter on the line. Your fabricís edge is now on the straight of grain and is ready to start being cut for very straight strips, without wonky edges or raveling edges.
Sometimes, when you are pulling the thread, the thread may break part way across the fabric. Cut along the line that you have pulled so far to the area where the thread broke. Then continue pulling the same thread if you can find it or start pulling another thread that is along the pulled line.
I check that the cut edge of my fabric is at right angles to the selvedge. Sometimes it isnít and then you have to pull and stretch the fabric along the bias of the fabric to get it back straight. You can also wet the fabric and block it back into shape.
This extra step may not be real necessary if you are just cutting small pieces, but I would not ever cut a long strip of fabric without straightening the edge like this.
I hope this helps. Let me know if you try this and how it works for you!