Lube it or lose it
Keeping your bike chain and cassette clean and lubed is one of the best ways to maintain your Bicycle. The best time to lube your bike is after a wash and or degrease.
Once your bike is thoroughly dry and positioned safely, you'll need clean rags to prepare your chain to be lubed. Make sure your chain is clean by pressing on the chain with the rag on both sides and spin your crank ring backward.
After the chain is completely clean apply a drop of lube on the top of each link as you slowly spin the crank ring. The lube needs to work its way into part of the chain.
Allow the chain to soak in the lube a bit and then repeat the first step. Clean off any access lube from the chain using a clean rag.