Just water the day before so that the dirt sticks together kinda like a sand castle place ur hand on top of the soil with the main stim between ur middle and ring finger to help keep it stable then keeping ur hand on the soil flip it over and pull the pot off with ur free hand and set in ur prepared pot and finish topping it with soil give a light water
I use a different method to this myself. My technique is as follows:
Firstly, the plant should have rooted out it's current pot well, so there is a well established rootball to work with. This ensures that the soil area is efficiently used, and also makes transplanting much easier.
I always repot when the soil is at it's dryest point, just before a watering is due. I simply squeeze lightly around the sides of the pot, and apply some gentle force to the base, to ensure the soil mass doesn't stick to the pot when it is removed. I then hold on to the base of the plant's stem, and gently pull the pot downwards and off. Because there is plenty of root mass and dry soil, the pot will come away easily, and the root mass will stay in one piece.
I then place the plant in the new pot (in a hole which has been premade to the size of the previous pot), and add extra soil if needed. I then water in thoroughly, and the job is done.
I hear a lot of people turning the plants upside down when repotting, but this is not necessary when using this method, which is especially good when your plants are several feet tall.
I should also note that in all my time using this method, I have never once seen the effects of "transplant shock", which many people seem to suffer from.
As for 24/0 vs 18/6, there is always much debate about this. Either way will work, and the resulting yields are similar (which I suppose means 18/6 is preferable, since you will save energy/money). However, I personally use 20/4, since I have seen research which indicates it may give larger yields than either 24/0 or 18/6. It's all down to personal preference though, so go with what you think is best for your situation.