Pour a shot (or however much you like, really) of whiskey into a glass. Fill the rest of the glass with cranberry juice.
This drink requires quality ingredients. It needs to be good whiskey, like Jameson's or Jack Daniel's. Cheap stuff like Bell's kills this drink dead. When ordering in a bar, the JD is probably your safest bet because they always have that.
The same goes for the cranberry juice. I tried the Safeway own-brand stuff and it is not good (what the hell did you put in this, guys? BAD Safeway). I go with the expensive Ocean Spray cranberry juice. Even then, you need to make sure you don't get the 'sweetened' version. We want the hard-core version (which, I see from the carton, is still 75% water, but hey).
With the right ingredients, this drink is absolutely delicious.
A friend of mine, on tasting her first Whiskey & Cranberry juice, remarked "That drink would make me sleep with anyone." What further endorsement do you need?