Double bucket method is very simple,1 bucket with clean water and 2nd bucket with shampoo/water solution, from shampoo bucket you MF will go to ride and will come back to clean water bucket and than again to shampoo bucket, maintain this cycle, you can also youtube it for better understanding
NXT is very good wax no need to buy Ultimate wax
Just buy clay bar and use it according to instruction, clay bar is the main thing to start with & it will make your ride surface smooth
1----Wash your ride
2---- Clay bar it according to instruction, you can watch demo on Google/you tube
3---- Again wash your ride and produce to next step which is polishing.