Just because you cannot see the buildup from below, it doesn’t mean that it is not there. We recommend that you tackle this task twice a year—once in the spring and once in the fall, when your yard gets the heaviest rain and leaf accumulation.
extension ladder with stabilizer attachment (this is so the ladder doesn't have to rest against the gutters, which could cause damage)
hose with sprayer
plastic garbage bags (or, ideally, compostable paper leaf bags)
rubber-soled shoes (to prevent slipping)
patience (this job can take several hours if your house is large).
What to Do
Place the ladder at one end of the roof so you can reach into the gutter without much leaning or straining; then you are ready to climb up. Wearing gloves and using the hand trowel, scoop the leaves and debris from the gutter and drop them onto the ground. Keep going until you've gotten out all of the gunk that you can possibly get out.
Move the ladder over a few feet and repeat on the next stretch of the gutter. Continue this process and repeat until the whole gutter is clear of leaves and debris.
Use the sprayer to flush out the gutter. Make sure that you direct the stream toward the downspout.
Come down from the ladder and rake up the debris that has been scattered throughout your yard. Place it in as many garbage bags as you need.