There are just a few steps to follow in order to maintain gutters yourself. My first recommendation is to climb a ladder and clean the goop out of the gutters. The decomposed leaves make great mulch or compost. Pay particular attention to the downspout. If leaves and debris are clogging it, water won't drain properly, and along with mildew and mud you'll end up with sagging gutters.
Next, check all the spikes that are supposed to go through the gutter, through the fascia board and into the rafter behind it. At most homes, these spikes miss the rafters entirely, usually because the spike has just worked its way out of the hole over the years. It's a good idea to invest in new gutter spikes such as the OMG FastenMaster, so the gutters are securely fastened once again.
Another thing you want to look at are the sources of any leaks, including holes in the gutters and cracked caulking in the seams. Use an old chisel to scrape the old caulking out and dry the area thoroughly. Then use new bead silicon sealing to keep water from getting down behind the gutters and rotting the boards.