Brass Sponge over Wet Sponge
Keep your soldering iron tip from oxidizing.
As it gets dull and gray, it’ll be harder to make good solder joints. My favorite tool to clean a tip is a Brass Sponge. The other option is a damp cellulose sponge, but I’m not a fan of those.
I have just never found a sponge gets the tip as clean as a light dabbing from the brass sponge.
Just be careful not to “scrub” too hard, you don’t want to scratch the tip. When you done soldering, make sure you clean it with the sponge then coat the tip with fresh solder. Leave that solder on the tip until the next time you use it. The layer of solder will prevent oxidation from building up while the iron sits unused.