Short answer is practice and break down the move into segments..
Instead of 180's try 90 degrees and an intentional pause to make sure you have a stable hover at that point. Then finish your rotation.. Many times you'll find that you have too much slip or too much lift at that 90 degree point and that's where you are losing your static tip point.. JB's Basic Hover drills video will make a huge improvement in this stepped maneuver for you.
As an interim drill, draw squares with your leading edge.. (90 degrees on right tip followed by 90 degrees on left tip rotating the same direction on the opposite tip, repeat until your LE has formed a perfect square in the sky and kite has made exactly one full rotation.)That will help you discern your hover when vertical as well as the transition between the maneuvers. Try flag out for verticals and then flag in.. (Sail on outside of square when vertical followed by sail on inside when vertical..) Basically start with kite upright for first drill and then start next drill from inverted start. It sounds harder than it actually is but it will attune you quickly to your kite and establish foundations to build upon. It will also help you see the sky as a grid since you are literally drawing LE sized squares on your field of vision.
There is not really any particular starting handle position for this move, since it can be initiated from any direction, position or other move that you are doing. One way to learn tip turns (pivots) is to fly SLOWLY in a circle in either direction and keep making the circle smaller and smaller until the kite is pivoting around the tip. You can even make it pivot around the top tip of the upright if you make the circle small enough. Usually it will be easier for you in one direction than the other. Practice both directions so you can do both equally well. Spend some extra time in the direction you find more difficult. On a side note, if your lines, bridle, etcetera, are not all symmetrically adjusted, one direction will always be "a little bit off".
There isn't really a good way to explain how to do this. It will come to you automatically if you just practice making your turns tighter and tighter each time you fly. Basic explanation is that you are retarding motion in one tip while flying the other forward. That means brake to one and forward to the other.
Ladders will look better, once you have your tip pivots down pat, if you abruptly stop all motion at the end of each half-circle. There is no miracle instruction that will allow you to just go out and do this instantly. These are refinements of the moves you are already doing that will become smoother and tighter with time spent flying.
Watch the basic control tutorials and keep an eye on what JB does with his hands.