This is hard to describe without pictures so either a tutorial with pictures or a video would be the way to go. I don't use any special rulers or tools.
One thing I would like to add however is that most tutorials suggest you stop 1/4" from the end when you are sewing toward a corner. This is assuming that you are using a 1/4" seam allowance. I use the width of my walking foot for a seam allowance when sewing on my bindings which is more like 3/8" therefore I stop 3/8" from the corner rather than 1/4". The rule here is to stop the distance of your seam allowance.
Another tip for achieving crisp miters on corners whether they are 90 degree corners or otherwise (60 degree for example) is when you fold your binding up at the corner make sure the binding and the raw edge you will eventually be sewing on after you turn your corner are in a straight line. You can use your ruler on a flat surface to double check. With a 90 degree corner by keeping the binding and the raw edge along the other side in a straight line this will give you a nice 45 degree fold. You can then either pin or hold on to this fold with a finger and bring the binding down along the raw edge you will be sewing on. If you have something other than a 90 degree corner your fold will be at a corresponding angle and not 45 degrees but the process is the same.
One thing that might help you in mitering the two ends when you are joining your binding at the end is to make a sample that you can keep handy along with some notes in your own words on how you did it. When I was teaching my daughter-in-law how to do it she took pictures at each step and so when she had to do it when I wasn't there she had those to refer to. There are multiple methods to do this and you just need to find one that works with your way of thinking. The first way I was taught to do it was so complicated but made perfect sense to the person teaching it. I searched and found a better way for me.
One tip I will add for mitering a binding at the end is that when I get ready to pin my two ends together (after I measured and cut them) I take a binder clip (like you get at an office supply store) and clip a big pleat in my quilt behind where I'm working so I'm not fighting with it as I'm trying to twist and sew the binding. The binding ends are free and longer than the pleated quilt at this point. Another tip is that once I sew my miter I never cut the extra off until I'm sure the binding fits and I've sewn the miter in the correct direction!