I'm a little late with this, but there are still a few days of the sale left. 

Steam is currently having one of its periodic fire-sales. Hundreds of games on the PC digital distribution service are currently marked down to prices apparently set by Malfunctioning Eddie. Steam has sales every weekend, but these major sales take on a particular structure which lends itself to a strategy when deciding what to buy.

I start by making a list of games I want. Feel free to derive inspiration from my own list:

• Painkiller
• The Maw
• Jolly Rover
• Lead and Gold
• Battlefield: Bad Company 2
• Saira
• Overlord 2

Steam makes maintaining this list easy now with the Wishlist feature. Simply add all these games to your Steam Wishlist. Now, it may be a good idea to go through the sale listing and see if there are any games you missed. Here's the important (and most difficult) part of the strategy: restraint.

You'll be tempted to immediately blow your load on everything in your wish list that's on sale. In my case, that's Painkiller, The Maw, Lead and Gold, and Overlord. What you need to do is exploit the structure of the sale I mentioned previously. These sales consist of a number of games that are on sale for the duration of the sale along with daily deals. Often, the two overlap. What is on sale for the duration may go to a daily sale at some point. That's when you want to buy as these markdowns are even more dramatic than the regular sale. Keep your list nearby, and check the daily deals each day. Until today's sale goes up, Overlord 2 from my list is currently one of the daily specials. The game is currently $6.79. The entire Overlord series (including Overlord 2) is on sale for $4.50! I am buying it at that price. I will save the rest of my games until the last day of the sale (July 4th) or until they are a daily sale item, whichever comes first.

Using this method, you will get the most out of Steam's big sales. Nothing hurts more than buying a bunch of games as soon as the sale opens only to see them one-by-one come up as the daily deal for an additional 20% discount over what you paid.

Have fun, and be sure to save some money for the rent!

Oh yeah, rent!
 
This is exactly my strategy, though there is also waffling combined with impulse morning buys before the sale ends.

That's exactly what I sort of do. However I doubt they will have assassin's creed 2 on sale for the daily deal, i'm going to buy it on the last day.

Waiting out for Shadow of Chernobyl here, but caved on like a few games which were like less than £2. 
 
Goddamn I hate steam.