First of all, please check out Mr. Malty’s site, specifically the FAQ on yeast starters. This will provide more information then my measly tips. Want to know what a yeast starter is? Read the FAQ.
So here are some tips on making a starter
Use a flask
No, not the fun flasks, but one of the lets not blow up in our face when playing with hot and cold liquid type flasks. Behold the wonders from the lab, borosilicate glass Erlenmeyer flask. If you can, get one at least 2x of the volume size then what you need. Alas we have been doing 4 liter starters so we can get all that headspace that we would like.
Add dry, then wet
If you follow the tip that you need 100 grams of dried malt extract (DME) for each liter of starter, you can throw that flask on the scale and add your DME. Why add DME before water? Any water near DME seems to turn it into some sticky sludge that is impossible to do anything with. Bonus points for getting to lick your fingers.
If you are going the yeast food route, add this now as well.
Hot wet
So you got the DME in the flask. Get your tap water as hot as possible and add it up to the volume you need. I am currently making a 2.5l starter so I have 250g of DME and I added 2.5l of water into the flask. They put some plastic wrap over the top, hold it tightly and shake away. If you have the head space, you can do more of a twirl then a shake and skip the plastic wrap.
Getting all that DME disolved in the water makes a huge difference. All of sudden you have fewer boil overs and less floaty shit in the starter.
Git it going
Take a piece of tin foil, place it on the top of the flask, smush it down, and tightly crimp it to the side of the flask. Most people recommend that you loosely apply this but I have found steam works its way out and when the starter boils up, it is less likely to just let those bubbles run down the side. Now of course, playing with heat, steam, and pressure is a dangerous thing so you are on your own. Insert some disclaimer that you are responsible for your actions, not my stupid ideas.
Cool down there little buddy
From here it is just a matter of throwing it on a ice bath (see disclaimer above), get it to 70f asap, put it on the stir plate, and pitch your yeast.
Keeping it happy
In the winter I wrap a fermwrap around the flask to a controller and tape the sensor to the side of the flask. Set it at 70f and you should be good to go.