Bonnet tiles and valleys

Hi

I'm about to tile my hipped roof. As I need to cut the tiles for the bonnets and valleys that butt up to them should I tile the roof and then do the valleys and hips last?

Also I know I need a lead saddle and also at the end of the ridge but should i put in lead soakers at the bottom of the valleys under the tiles and if yes how high up do they need to run?

Any advice appreciated

Thanks