Before we get onto binding you'll need to square up your quilt so the corners have right angles and the edges are straight.
Like basting you'll need a large flat area - or use the half at a time method again.
Start at one corner and position your cutting mat underneath. Use your longest ruler to cut a straight line along one edge of your quilt and removing any excess batting and backing. Move your cutting mat as you go.
Repeat for each remaining side making sure you are getting a good right angle in each corner. If you have been really accurate your first and last edge will meet naturally in a right angle at the last corner. You can double check how even you have been by folding the quilt diagonally, corner to corner, and checking that everything lines up.
Now for the binding!
Binding is a strip of fabric which, you guessed, it binds the raw edges of the fabric and batting and prevents them separating and protects them from fraying. You can buy it by the length but I like to make mine so that I get exactly the fabric I want for my quilt.
Many quilt patterns simply say: Bind as desired. Typically quilts are bound using straight grain binding. I like to use a 2 1/4'' strip to make mine. Measure the perimeter of your quilt and add 20''. Divide this new figure by your width of fabric (WOF) to calculate the number of WOF strips you will need. The width of your strips will determine how much actual yardage you will need. Quilt patterns will be generous so I'm sure you will have enough!
Join all your strips together. you can use a straight seam just fine but a diagonal 45 degree seam is stronger.
Next you need to fold your strips in half, wrong side of the fabric against wrong side. You can buy gadgets to help with this but I use a simple pin and my iron. Watch this...
Now to sew it on. Like everything else with quilting how you sew on your binding is also a matter of preference. So experiment with techniques with each new quilt to see what works for you.
I like to machine sew the binding to the front of my quilt. Lay your binding along the edge of your quilt, raw edge of the binding lining up with the raw edge of the quilt. You can pin or clip it or not, as you prefer. Start sewing some distance from the corner making sure you leave a length of binding loose.
Stitch all along the edge with a 1/4'' seam allowance, using a mitre fold at each corner.
There are several ways to join your binding ends but the simplest is using a straight fold. Simply fold the raw end of one end under itself and tuck the other end into it. You can continue your 1/4'' seam right over these ends until everything is secure.
Then attach your binding to the other side. You can machine sew this but many quilters like to hand finish.
To machine stitch the binding, choose a thread colour that will blend in with the fabric on the front of the quilt and from, the back stitch as close to the edge of the binding as possible.
To hand stitch choose a strong thread, maybe a hand quilting weight, and use either a running stitch or a blind stitch. This is my favourite way to do it and I often save it for some sofa and Netflix time.
Now you can feel very pleased with yourself, your quilt is finished! well done!