What a sick, sad world we live in where most bartenders don't know how to make a decent martini, yet they charge you $9 for it and put in the same effort required for a rum and coke. I don't blame the bartenders. They are simply doing the wishes of those who give them money. Nay, it is the fault of those ordering these "whatevertini" abominations. Genpop has been coldly and persistenly raping the good name of the martini since James Bond first sidled his smug self up to a casino bar and asked for vodka where gin should be! I'm not going to post a how-to, but here are some pointers to correct common mistakes:

1. A martini is always made with good gin. I prefer Bombay Sapphire or Tanqueray. No vodka.
2. A martini is always "up." There should be no need for rocks because it's served ice cold. The mixing of the drink with ice should provide enough dilution to take the edge off the alcohol. The glasses should be pre-chilled with ice-water before you start mixing.
3. If possible, use whole cubes of ice with no small pieces. This will prevent overdilution. Also, the gin should be poured into the shaker after the ice, but not over the ice, again to prevent overdilution.
4. Some prefer to shake, but a gentle swirling motion does just fine. The shaker should be too cold to handle, so use a dry cloth. Swirl until the cloth freezes to the side of the shaker.
5. The amount of vermouth is a matter of taste, but it should be very little. About 1/2 jigger is enough if you are making two martinis in the same shaker. If someone asks for "dry," then cut down the vermouth. For example, you can put the vermouth in the glass before pouring the drink, coat the glass by swirling, and dumping out the excess.
6. Olive juice is also a matter of taste, but it should also be added after the drink is poured, if at all. If someone asks for "dirty" then I use about a half jigger of juice and a little more vermouth.
7. Don't order a martini in a busy bar unless you like phlegm in your martini.