Mike..
The best way, in most cases, is to get more height. Generally, but now always, 30 feet is better than 20 and could make the difference. Also be sure you have good line of sight. Better cable always makes a little difference..RG-6 Quad should be minimum requirement. I do not know your entire setup so can not say anything about a line amp or a pre-amp on your mast close to antenna. Generally, a amp will give back to you some of the signal you have lost along the way...after getting to your antenna.