The M looks complicated, but don't let it intimidate you. It starts with two strips of fabric sewn to a triangular piece of your background fabric to make a V shape.
Add some background fabric to either side of the middle "V", then sew your letter fabric uprights to either side of that.This yellow M from my sampler quilt, Letters From Home, is OK, but the V almost looks like a hammock. There isn't enough of it connected to the uprights on either side.Here the green V is well anchored to the uprights on either side. That middle V shape can touch the baseline if you like.The strips can be both thick and thin.
The center V shape can be wonky, as in the above examples, or more regular and precise, like these below.In this blue M, I wanted the fabrics to make the letter look like the fabric was folded over itself. The strips are all on the wide side, and all the elements have the same "weight."This M from No Rules for Julie is one of my all time favorites. The strips are thinner and the letter is narrower.
Make your center V shape, then move the uprights on either side around until the letter M looks appealing to you. Then sew the strips. Don't be afraid to play with it a bit first.