Metal gutter leaf protection screens are the least expensive and most effective form of leaf protection.
The prefered method of installation is to slip the back edge of the screen under the starter course of shingles, then hook the front edge of the screen to the front lip of the gutter and secure with zip screws.
These gutter screens allow for easy inspection and cleaning without removal. Just spray water from a garden hose right through the screen, flushing the debris down the downspout and onto the ground. These screens will keep out leaves, branches, pine cones and toys that will quickly clog your gutters.