How do I lubricate my chain? I know I should lubricate my chain regularly. I got some lube at my LBS; how should I apply it? Do I just drip some on one spot, and turn the pedals around a few times to spread it out? Drip it all over the chain? Do I clean the chain first? How can I tell if it needs lube, or if I've put enough on?
Clean the chain first - see this question or this question.

If the chain has a master link I like to start there just so I can keep track of which links I have lubed easier.

Usually you should shake up the lube, especially if it is a 'dry' or 'wax' formula.  Then drip 1 or 2 drops on the rollers of each link.  Lube on the outside of the chain is basically worthless unless you are applying a 'wet' lube for weather protection.  More than one or two drops on each link will be too much, and will drip a lot of lube onto the floor or ground where you are working.

Pedal the chain backwards and get every link.  When done run the chain through all the gears. Let the chain sit for a few minutes then using a clean, dry, lint-free cloth, wipe the excess from the chain, cogs and chain rings.