Discardia is an attitude as much as an act. You don't need to make a lot of massive changes all at once or do every activity I suggest to be a discardian; just commit yourself to change and take more consideration about what new things you bring into your life.
Do what you can. If you don't have time or energy to clean that closet, just do 30 minutes on it or go through the things on one shelf.
Don't fall into the trap of spending a ton of money on new organizational toys unless you're really sure you'll get enough benefit from them. Maybe before you buy that expensive storage compartment system, you should dry-run the concept with some stacked shoeboxes. Finish your first rounds of purges before you lock yourself into a new arrangement for things.
Whatever you do though, do a little something that starts you moving in the direction you want to go.
Do one thing, just a little thing, right now.