Step 1: Ingredients
Pick something cheap, but still drinkable. If you wouldn't drink it, don't use it.
You need about 1 pound. Less will work, but it will make the final product have a more subtle taste.
I personally use mason jars, but you can use old liquor bottles, jars, cans, or whatever. You should probably use glass, as the plastic will impart a bad taste to the vodka.
Step 2: Cut the Strawberries
This step is a lot easier with a kitchen knife and cutting board. In a pinch, a pocket knife works just fine.
I found that about a half of a pint of strawberries will flavor about a pint of vodka, but the measures are quite variable. Basically, the less strawberries to vodka, the more subtle the strawberry taste.
Step 4: Let it Sit
Then forget about it.
Because of the alcohol, you don't have to worry about this going bad for a very long time. Leaving it in the fridge for about two to three weeks is about the minimum time that you should let it infuse. You can drink it as soon as you want, but it won't taste as good.
This drink does get better with age, to a certain point. I found a jar of this that I left in the fridge for about two months, and it was the best strawberry vodka that I've ever tasted.