Put on work gloves. Place a ladder at one corner of the house. Climb the ladder with a gardening trowel in your hand. Scoop out all dried leaves and twigs with a gloved hand. Slide the trowel in the bottom of the gutter to remove any wet debris. Work around the house to clean all of the gutters.
Measure the vertical depth of your gutters with a measuring tape. Add 3 inches to the measurement and cut pieces this size off a roll of gutter screen with tin snips. If you purchased precut gutter screen, skip this step.
Climb the ladder with several lengths of gutter screen and a pair of tin snips. Hold a length of gutter screen over the gutter with one hand. Insert about 3 inches of the rear edge of the gutter screen underneath the first row of shingles.
Align the front edge of the screen on the gutter. Press a gutter clip over the front lip of the screen and into the slot in the gutter. If you purchased gutter screen that does not use gutter clips, place the front edge of the gutter screen inside the gutter and slide it into the crack at the front of the gutter.
Continue adding lengths of gutter screen to cover all of the gutters. Overlap each length by 1 inch on each end. Snip any gutter screen away from protruding objects so the screen lies flat on top of the gutters.