I posted this on another thread and thought it might be helpful here:
Regarding the starter, what you are looking for is a starter wort with an OG of about 1.025 to 1.030 regardless of your beer style. This gravity promotes yeast growth. A 2 quart starter is recommended for ales, for lagers it's a full gallon, the more yeast the better. With this much starter wort, I like to start 3 or 4 days ahead so that the yeast ferments and settles out so I can decant off most of the liquid before pitching. I personally like to weigh my dry malt extract (DME) rather than measure by volume. DME gives about 46 gravity points per pound per gallon of water. If you run the numbers, 5.2 oz of DME in 2 quarts of water will give you a gravity of 1.030. Boil 2 quarts of water in a large pan (at least 4 qt), remove from the heat, SLOWLY add the DME (it will foam like crazy, be careful), then bring the heat back up while stirring to dissolve. Boil for 15 minutes, then submerge the pan in cold water until the temp is down to 70 F or so. Stirring the wort with a sanitized spoon and moving the pan around in the water (gently) will speed the cooling. Pour the wort into a gallon sized, sanitized, glass jug. Make sure everything that touches the wort is sanitized. Add your yeast, cover the opening with a sanitized piece of foil, hold tightly and shake it vigorously for 10 - 15 seconds to aerate. Remove the foil and put on an air lock (sanitized of course) and wait. About twice a day for the first couple of days, give the jug a swirl to keep the yeast in suspension. After this, let the yeast settle out.
If you make your starter Tuesday night and brew Saturday morning, the yeast will have mostly settled out by pitching time. I like to decant off most of the liquid, and in fact, I will pour some in a small shot glass and taste it. Be sure to flame the mouth of the jug before pouring. If the sanitation procedures are sound, it should taste nothing like beer, but should taste clean and free from whangy off flavors like those typical of infection. Leave a pint or so behind in the jug, swirl up the yeast, and pitch.