I would wager that at least 75% of all the port we buy is purchased in December.

It seems to be par for the course. For some reason, we think: "Oh, Christmas is coming. Better get the customary bottle of Port in."

I have no problem with this being a tradition. I happen to like port (quel surprise), and the seasonal sales swell always reminds me of this, so I usually get in on the act too. The only downside to us buying port sporadically is that we rarely get chance to become particularly 'expert' when it comes to choosing the right one.

So, rather than leaving you to buy any port in this year's retail storm (boom-boom), here's a quick guide to the different styles out there and a few specific recommendations.

Port is a fortified wine produced in the Douro valley of Portugal, and has long been popular in Britain, since the early 18th century, when everyone else in Europe hated us too much to give us wine. We got stuck right in, and industrialised the area into making wines fortified with a wee bit of grape-based spirit, which increased alcohol content, and in turn sugar, by stopping fermentation.

The point of this exercise was to make fine wines that could survive the long journey from Portugal without spoiling: as you probably know, ports tend to keep a little longer than 'normal' wines, both before and after opening the bottle.

Our historical involvement in that industry is still clear as many of the major port houses still bear strikingly English-sounding names, like Graham's and Taylor's.

Most cheaper ports are labelled 'Ruby Port', or 'Finest Reserve' (they both mean the same thing). This style is a simple blend of port wines from numerous vintages, often blended to a house style, much like non-vintage champagnes. Having had a minimum of oak ageing and invariably being drawn from very recent vintages, these are light, fruity and agreeable. You  won't normally find sediment in ruby ports, either - you just pop the cork and go.

A good entry level port to get you started is Dow's Finest Reserve Port (£6, down from £10.99, Sainsbury's). This is a pleasant and lifted port with more than enough complexity to make it stand out from the crowd. Showing a lot of red fruit, but with a slightly darker peppery finish to round things off - ruby is a simple style, but you don't want it too simple.

Next up are the vintages. The junior partner is LBV (late bottled vintage), which has seen a long spell of years ageing in oak before bottling. These are invariably released ready to drink, but will often keep nicely in bottle for a few years. LBVs are usually a bit fuller bodied than the ruby style, and show a lot more dark fruit and spice.

Vintage ports are only produced in exceptional harvest years. These spend a period in oak, but the in-bottle ageing is the key part, so you'd be looking at buying these in older years if you wanted to drink now, but be prepared to put these down to age for a while. You get into premium vintage territory when you buy 'Single Quinta' vintages (single estate), but be prepared to part with a pretty penny for these.

Here are a few good examples of ready to drink vintages. Taylor's LBV 2008 (£10, down from £14.90, Sainsbury's), a good value port that's just old enough to drink now, but no pressure - it could cellar for a couple of years yet!

For a proper vintage, try Sandeman Vau vintage 2000 (£21, down from £26,Oddbins) which is utterly ready to drink now, and shows a lovely, chocolaty spice with a mouth-feel like liquid velvet. They say that for Port, 2000 was a vintage of a lifetime, so why not go the whole hog, and try the quite incredible Quinta do Vesuvio 2000 (£53, Oddbins, limited availability)?

Tawny and white ports are made more in the aperitif/digestif style. Some white ports make a delicious, dry pre-dinner appetiser, and many tawny ports present fantastic alternatives to dessert wines. White ports are produced from white grapes (duh), but are often oak aged, dulling the colour, whereas tawny ports are oxidised which has the effect of decreasing the opacity of the wine, and lending it a rich brown hue.

An old favourite is Warre's Otima 10 y.o. Tawny (£10, down from £12.50, ASDA). It's a beautiful rich auburn colour and has a great intensity of warmly spiced sweetness. Have it with Christmas pudding, and pour a little on the cake while you're at it.

Now you're sorted and ported.