As you can find in many of my posts I believe one of the most important factors of having good style is attention to detail. The way you knot your necktie is just another detail that needs to be brought into awareness.
The two basic knots are the Windsor and Four-in-Hand. Many men simply learned how to tie one or the other and it has become the knot they tie without much thought going into it. Factors that will dictate which knot should be tied include what type of collar is on the shirt and the personal taste of the wearer.
The Windsor is a symmetrical knot that tends to be very broad. Most men tend to wear this knot with spread collars as it easily fills the space. Over the past few years it has become somewhat of a fad to knot your tie in a distractingly large Windsor knot (as seen here). This I feel is a poor choice due to the excessive attention the knot draws. This is a good knot but I suggest that to stay away from the extra large variety. Personal taste may cause some men to become bored with the Windsor varieties due to their symmetry.
The other knot mentioned above is the Four-in-Hand. Its asymmetry has the benefit of adding subtle interest that doesn’t look overstudied. The knot also has the flexibility of being tied in small or, through a variation in tying, can be much larger, depending on the collar it is being paired with or the wearers personal taste.
This is Prince Michael of Kent who’s trademark is his large Four-in-Hand knots. A very large knot that some may say does what the Windsor above does but the fact that it a Four-in-Hand adds a bit of asymmetric charm.
Tie material and tie lining will also add to the size of the knot you create. In order to find what you prefer to wear with different collars you can only experiment.
Here is a link to some easy to follow instructions for a wide variety of knots.