Water changes, and if your tank is large enough, you can add some sort of algae eater as long as you don't have fish that are likely to get bullied. Pleco's are NOT algae eaters. They make products that kill algae too. Good filtration can help. They also have magnet glass cleaners at pet stores that you can clean the glass with, and you can also try gravel vacuuming the substrate.
I do weekly water changes and I use the gravel vacuum every water change. I have two moss balls. Unfortunately I cannot get any more fish because I'm just under capacity for them to be comfortable. I'll try to get the magnet and just remove all I see and see if that helps.
We got a very small bristlenose pleco. Like barley and inch. He was going to town on the brown algae earlier, but I had a fish have fry so I had to spend time taking the tank apart finding drys so he's hiding for now. He's really helped in the little he did