Easiest? Hard to say. It is easiest for me. I think that anyone who is fit enough and coordinated enough to use climbing sticks can learn to climb 2TC. The first thing to really look at is what type of trees do you have to climb in your hunting area. I have an overabundance of straight, limbless trees in my area. 2TC really shines on these types of trees. Limby trees are more problematic. You can advance around limbs, but it will slow you down and adds complexity as with any climbing method. On a straight limbless tree, I can be at hunting height of 20+ feet in about 7 minutes from the time I walk up to the tree and about 2 minutes of that is set up at ground level. It took me about a month to get to that point.
2TC is pretty simple. There are three main parts. You should already have a saddle. This is the first part. You should have a main tether. This is the second part. Now you will need a foot tether. A foot tether is just like the main tether at the top, and at the bottom will be some form of loop, usually on some form of adjustment, to vary overall length to account for the differences in tree diameters.
The top tether goes around the tree just above head height. The foot tether goes a few inches under the top tether. The foot loop should be high enough to step up into comfortably. Clip your saddle bridge into the top tether's carabiner, put the saddle under your butt and tighten down the waist belt. Now you want to put the arch of your foot into the foot tether's loop. Push down while digging your toe into the tree to stabilize you. Step up into the loop and at the same time put your opposite leg up against the side of the tree for balance. Hold onto the tree with your hands as you are stepping up. While balancing this way, reach up and advance the now slack top tether about 18 inches. Now, slowly sit back into your top tether. At this point I take my foot out of the foot loop on the foot tether and then advance the foot tether back up to its position under the top tether. Then repeat this process until you are at the desired height. Reading through all that you are probably thinking "I can't do all that while balancing on one foot!" I couldn't do it the first time I tried it. It really is just getting that one simple set of moves down. It really is simple once you do it a few times. If you read through the "Why don't y'all 2TC" thread, you will see my progression and struggles. I stuck with it and now it works really well for me.
Try it out low and slow. Don't try to go high and don't try for speed. Just try to get that one move up and one move back down in reverse down pat. Once you have that down you can go as high as you want. This is the learn to crawl before you can walk stage.
I would also recommend using large ropes in the beginning. I used 11.4 MM Bluewater static for my top tether and 11.4 MM Sampson Predator for my bottom tether. Once you really get the method down pat, then start streamlining everything if you want. Don't get caught up in complexity in the beginning. Just learn the moves.