Prep your fabric carefully before you start to cut out your pattern pieces by washing it at a normal temperature. Allow it to dry naturally and avoid over pressing it flat.
Treat your fabric gently and try to avoid over handling.
You can trim off the selvedges if they are very wiggly.
Don’t worry if the cut edges or the selvedges of the fabrics don’t line up perfectly once you have found the straight grain. Knit fabrics can often warp as they are rolled or blocked onto boards.
Once you have decided which is the right or wrong side, use a marker or chalk to mark the wrong side.