I know it's vermouth again, but bear with me a little. We'll also have a little look at shaking & shakers. Generally speaking French vermouth is dry, whilst Italian is sweet. Red vermouth is generally the sweetest & adds a pretty good colour to a drink. A 50/50 mix of dry & sweet vermouth used in a spirit & vermouth cocktail is generally referred to as "perfect", ask a good bartender for a perfect Martini & that's what you'll get. Its a good idea to keep both in your cabinet.
The shaker is the iconic cocktail tool, there are two main types, the boston, which consists of a glass & a tin that fit together and are held in place by the contraction of the tin, and the Cobbler which is all metal. You are probably thinking of a Cobbler shaker at this point, which comes in 3 parts. A tin, a strainer and a cap. You fill the tin with ice & ingredients which can often be measured using the cap, fit the strainer, fit the cap, shake hard remove the cap & pour. These kind of shakers can be had quite cheaply, you ought to be able to pick up a reasonably nice one for £5-10 from a second hand shop or on line. Of course you can spend more and get silver or designer or antique, its up to you.
3 parts Gin
1 part sweet vermouth
1 part Grapefruit juice
1-2 dashes bitters
fill the tin of your shaker with ice, and then add the ingredients. I like to use pink grapefruit juice as it's slightly sweeter, but thats a personal preference. If you are using fresh squeezed juice you might want a finer strainer on had to catch stray pips & pulp. Fit the strainer & cap, check its a tight fit. With the top aimed over your shoulder, shake hard for 10-15 seconds. The tin should get very cold. Set it down remove the cap & pour.
Enjoy your drink, you've earnt it.
Next time we'll look at a different base spirit to gin and another classic cocktail.