Knots are an integral part of any anglers armoury, knowing of different knots, how to tie them and when to use, is just as important as choosing the right bait. When tying a knot, ensure all is correct before tightening, then do so slowly. Lubricate all knots in water (or in your mouth) Always check (by pulling it) that it will not come undone, and that you have not "kinked" the line, tying it. If you have, redo!
I've been carp fishing for a good few years now and have seen many changes, with some excellent new tackle and ideas.
One of the most important changes came in 1979, when Lenny Middleton and Kevin Maddocks started to use the hair rig. They actually used natural hair 2" long and had some amazing results. When this idea was publicised it completely changed carp fishing, and since then there have been lots of new rigs, but really the hair rig will always catch fish if presented properly.
My preference with hooks is a straight point with a slight inturned eye and I like to use the knotless knot and finish off with silicone tube, which helps the hook to turn into the mouth upon ejection.
The knotless knot in my opinion is the best way of attaching a hook to a hooklink for the Standard Hair Rig.
The Knotless Knot
The Knotless-knot is very simple and easy to tie. The knot simply utilizes the hooklength material to firmly tie on the hook and produce the hair of a desired length.

Tieing The Knotless Knot
1. Tie a small loop using an Over-hand knot at one end of your selected hooklength material, I’ve used a 12 inch length of braid in this instance. This loop for your boilie stop to secure the boilie in place.

2. Using a Boilie Needle thread the boilie (or whatever you’re using as a Hookbait) on to what will be the Hair.

3. Once the Boilie has been threaded on to the Hair a Boilie Stop is pushed through the loop to secure the Boilie in place. Thread a small piece of Silicone tubing on to the hooklength and then on to hook, before threading the hooklength through the eye of the hook.

4. Adjust the length of the Hair to your desired length, about 3mm from the end of the hook to the hookbait is my desired length of hair. Whip up the shank of the hook using a minimum of 5 turns.

5. Thread the hooklength once more back through the eye of the hook and pull tight.

6. Tie a swivel on to the end of the hooklength and you’re ready to go!
I always put a small dap of Super Glue on the knots just for piece of mind, but it isn’t necessary.

Using the Hair-Rig
Once the Hair-rig has been tied a Boilie or bait of the same size can be used on the same Hair time and time again as the Hair length has been set for that particular size of bait.
The piece of Silicone tubing that I use is to determine the position of where the Hair leaves the Shank of the hook, which is level with the hookpoint. This also allows the hook to turn and the rig to work, in a sense, as an anti-eject ‘Blow-Back’ rig. In other words, once the hook has penetrated the lip of the fish, the fish won’t be able to blow out the bait and hook, just the bait.
Other anglers prefer not to use a small piece of Silicone tubing, but instead whip all of the way up the shank of the hook until they are level with the hook point, which is fine.
Hair Length
In my experience, and whilst discussing Hair length with other anglers, I’ve found that there is no ultimate Hair length, though a gap of between 2mm to 10mm from the bend of the hook to the hookbait is favoured by most.
It’s a case of trial and error in finding a Hair length that works for the size and pattern of hook being used, the size of bait being used, the hooklength material and the way in which the carp are feeding. If you are missing runs or you feel the fish are picking up and successfully ejecting your hook and hookbait then a adjust the length of the Hair, which could make all the difference.
The same Hair-rig/Knotless-knot, but with a longer Hair.