Maintaining Levain

I keep two pounds of starter on hand in my fridge. I prep my starter the night before I am going to use it. If the starter has been in the fridge, I pour off any accumulated alcohol into the sink and discard half of the starter by weight, then replenish what I removed with equal amounts flour and filtered water.  

I leave it on the counter overnight. The starter usually spills out of the container overnight, so putting the container on a piece of parchment paper makes next-day cleanup easier. 

The next morning I remove a pound for baking, and add a fresh 8oz. of water and 8oz. of flour to my starter container, let it sit for 3 hours, and then I pop it back in the fridge. 
Some other helpful hints: 

•  Always maintain at least a pound of starter. 
•  If you bake every day, you don't need to refrigerate the starter; and if you use it often, you won't need to throw away any, you can use the pound you would otherwise discard. 
•  If I am going to need more than a pound, I build up my starter mass over a few days, doubling its mass each day.  I don't discard any starter when I do this, I just keep adding more mass. 
• I always discard any gray, discolored starter from the top before using it. 
• And finally, I don't discard the starter down the sink, as I'm afraid it could accumulate in the drain lines.