Pour out a small amount - about a sixth of a glass. Have a good look at the colour and write it down. Swirl the wine around, lower your nose into the glass and take a good, long sniff. Write down all the things the smell reminds you of, no matter how odd. Pears, petrol, rotten bananas, baby-lotion? The main thing is to record precisely what comes into your head.
Now take a mouthful, roll it all around your mouth before swallowing and, again, write down what it tastes like. Plum jam, burnt meat, mint-chocolate, Dettol . . .? Honesty is all - and those descriptions will help to fix the flavour clearly in your mind. Now, decide whether you like it and why. Later, you'll (maybe) start thinking about concentration of fruit, acidity, tannins, alcohol and length - but already you're a taster.