Making a starter is very beneficial to your yeast, and therefore your brew. Do it once, and you will wonder why you never did in the past.
Very simple process. Bring two cups of water to a boil and add 1/2 cup DME. Stir and boil for about 10 minutes to sanitize. Add this mixture to a bottle or jar of some sort and shake the living crap out of it to aerate. After that, pitch your yeast and cover with tin foil/plastic/airlock etc
This can be done as little as a day before or as long as 10 days before. I think the best case scenario is probably somewhere between one and three days.
Trust me it is worth it.