The first step is (sigh) back to dirt basics:
Grain: the treads in the fabric that run the length of the fabric.
Cross-grain: the treads in the fabric that run the width of the fabric
Self-edge: (selvage) the edges that are factory finished (not the cut edges)
The next step is to make sure the fabric is straight. Most fabric will twist out of straight of grain when washed, if you don't straighten it again you will have seams which are just fine until you wash the garment the first time then the seams will twist to the straight of the grain. An example of this is blue jeans that have a side seam that runs down the side for part of your leg then makes a bee-line for the front. The fabric was not cut on the straight of grain.
To check for straight of grain fold your fabric length wise with the self-edges even. Does the center of the folded fabric look smooth? If it has a wobble in it you will need another person to help you to pull the fabric on the bias to straighten the grain. A couple of gentle tugs on opposite corners should do the trick. Remember that the cut edges may not have been cut straight or ëon grainí and probably will not match up. Donít try to force them to match up as your focus is the center fold being smooth. Fold the fabric again and check the centerline fold. Repeat the tugging as needed. If the fabric is very wrinkled iron it before you continue. Now you finally get to layout and cut out the tunic. Just click on CUT.