I find that eating fat rich foods, staying under 10gm carbs total (regardless of the quality of carbs - as in broccoli = sugar) and low protein as well in the 2-3 days leading up to a fast can really help if you are doing it primarily for weight loss.
Protein has to be low because otherwise, your body will eat a bit more muscle especially if you're insulin resistant.
Carbs flare up insulin, so should be very very low.
I am still figuring this out, and no idea about the cleansing fasts at all.
When breaking a long fast, you want to start with pureed vegetables diluted with water first. 1-2 days of that and your gut bacteria will be up and cranking to move to good cruciferous veggies. I think - I have not done that correctly either.