HDDon gave some excellent points, and I just want to add one; change brake fluid - front & rear.
A clear piece of tubing over the bleeding nipple, other end into a plastic bottle. Open reservoir cover and bleed out the old fluid while keeping an eye on the level in the reservoir. I use a box wrench for the nipple, as it will hang in place while pumping the lever. You should pump 'til the reservoir is almost empty first, to avoid mixing the new & old too much. Just make sure you don't suck air into the plunger (adjust handlebars so reservoir is horizontal)...
Then you just keep bleeding until you see the new fluid in the tube (the HD fluid is purple & clear, your old will probably be brown & opaque).
Then, when your brakes are nice & firm, the trick to completely rid the (front) system of any air is to tighten a tie-wrap over the front lever holding it half-way in. Leave overnight, and all the tiny airbubbles that you'll never get rid of by normal bleeding will escape. Your brakes will now be as good as they ever can be...