12 oz tumbler. 4 ice cubes. 1/2 shot lemon juice. 1/2 shot lime juice. 1/4 shot worcestershire (a little more if you like it spicy.) 1 1/2 shots of vodka. (Note , cheap vodka gives you hangovers , quality stuff doesn't. There are some pretty quality vodkas that are not pricey. I personally use Gilbys or Gordons. Never got a hangover from either one. I avoid Skoal like the plague.) 1/4 teaspoon of Old Bay Crab Seasoning. 1 pressed garlic clove. Knife tip of horseradish (optional.) Fill with Clamato and shake the hell out of it. If you really like it spicy , a dash or two of Tabasco. I personally don't use it.
The best Bloody Mary I have ever had was at a place called "The Freckled Fin" on Bradenton beach in Florida. They also have incredible shrimp fritters.
As far as bottled mixes go , meh.