Tasting young red wine before it has been bottled is rarely fun. It can be intellectually extremely stimulating but such embryonic liquids with their high levels of acidity and tannin rarely caress the palate - they are more likely to assault it. You are strongly advised to spit everything out - should you ever be tempted to drink a wine, then buy it!
On a practical level I also advise you to wear dark clothes (young red wine stains horribly) and, obviously, go easy on the after-shave or perfume. Taste considerately. Make sure you are not in other people's way either at the tasting table or the spittoon.
In my opinion, unless you are a complete novice, it helps to taste solo. That way you can concentrate on your own impressions rather than worrying about whether they happen to tally with your friends' (they probably won't).
Usually you will be tasting a number of wines from the same young vintage. Do take special note of how the first few wines strike you because once you have become accustomed to that particular vintage's dominant character (particularly high or low acidity, for example) it will be very difficult to assess the vintage character. After the first few wines you will find it much easier just to work out individual performances within that general vintage character.
Depth of colour
Although much is made of this, there is no correlation between depth of colour and quality. In the old days when so many wines were made from underripe grapes, a deep red may have been an indicator that at least the grapes were ripe. This is no longer so, and many very deep purple/black wines have been unpleasantly over-extracted or may be unbalanced with too much tannin or alcohol. Colour is specifically not especially significant as a guide to quality in burgundy. Some red burgundies deepen in colour in barrel, but lightness of colour is no fault in a burgundy. I'd be wary of such a young wine with a watery rim though; this could be a sign of over-production.
Good red wines tend to look healthy - no grey tinge which is common in mass-produced commercial blends. They can be all sorts of red from deep purplish blue to mahogany, the more blue the more youthful it is. If a very young wine already has some orange in it, this suggests it may be evolving dangerously fast, but a blueish wine is not necessarily better than one that is more crimson.
Obviously you're looking for the character of this and whether you like it, is it clean and fresh, not too heavily obscured by oak etc.
(Sometimes however I come across young wines that do not have much obvious aroma but they manage to convince me that this is not because they don't have much flavour but because they are just reticent. Often this goes hand in hand with a wine with great concentration on the palate whose sheer mass is preventing the aroma from 'escaping' for the moment. This last category is not a very big one but worth pointing out that lack of aroma is not always a fault in my book.)
In young wines one is just looking for primary fruit aromas and perhaps some secondary aromas as a result of fermentation. One would not expect the tertiary aromas of advanced evolution. If they are there, the wine may be prematurely aged and not a good candidate for anyone's cellar.
At this stage the sort of aromas I might expect from a Cabernet-based wine would be cassis, minerals, cigar box, sometimes chocolate in a very ripe example, but always that suggestion of currant bush leafiness (not a fault in my book unless it is aggressively herbaceous). From young Pinots aromas are mainly in the red and black fruit spectrum with perhaps sometimes some spice, something autumnal (leaves, moss, occasionally mushroom). If there is a sort of green leafiness here this suggests the fruit may not have ripened fully. If there are coffee flavours the wine may have evolved too fast.
If there is gas, the wine may recently have been racked and this is not necessarily a fault. If there is oxidation, then one should not necessarily blame the wine; tasting samples may have been taken out of barrel days and occasionally unfortunately weeks beforehand so that the sample may just have oxidised. Best to try another sample if you can.
Here you are looking for the intensity of fruit but also the balance of the relative ingredients. It is natural to experience an excess of acidity and, especially, tannin at this early stage, before the various fruit components have knit together to form more complex and more significant elements to distract from the youthful acidity and replace the tannins which will eventually be precipitated out. The key question is really whether there are enough pleasant fruit components to see the wine through to an attractive middle age while the tannins disappear. Don't be afraid of tannin per se. Look for the tannin's quality - is it drying and aggressive or is it ripe, refreshing and stimulating?
If the wine is already rather delicious to drink straight out of barrel then this will probably be a very early-maturing vintage - although if there is a good charge of tannins underneath that is obvious only at the end of the tasting process then this is a very good sign that the wine has both a high level of fruit and sufficient tannin to see it through to literally a ripe old age. There is nothing wrong with an early-maturing vintage (see 2000 in Burgundy). They can be very useful but one needs to be aware and ensure one drinks them before some of the more stately vintages (1996 springs to mind).
You should try to assess the tannin quality and the point at which it makes its impact. Tannins can be anything from green through rasping to sandy and grainy and finally almost gentle and ripe. They can dominate the tasting experience from the moment you take the wine in your mouth (bad) or they can just gently insinuate themselves towards the end of the tasting experience (good). If the wine is really painful to taste because of its high tannin level and has a very deep colour, it has probably been over-extracted - never a positive attribute but really horrid with a grape as delicate as Pinot Noir.
Do notice also the impact that alcohol has. If your palate is left feeling 'hot' at the back after spitting out the wine (these are rarely wines one is tempted to drink) then it may well have an excess of alcohol which it will never shake off - though this is generally a much less common fault in Burgundy than in many other wine regions.
This is not as critical in my opinion as in a mature wine but beware wines whose impact disappears immediately on spitting. And be wary of wines which leave you with a very tart, hot or tannic impression at the end. This is likely to betray what will be their dominant element throughout their lives.