This is a big job, but you can sand your cabinets in sections. It helps to have a helper; even a child can help with instructions.
Note that the cabinet doors are stained laying flat. They should dry the same way, otherwise they will drip - even if they have been wiped.
The instructor sprayed the polyurethane on, but it is not necessary. He recommended two other types of finish, but if you have children - poly is the best.
This is another project using brush technique. here
If you have a bathroom cabinet with a similar finish as the kitchen, you may want to do the bathroom cabinet first. It will give you the confidence go do the kitchen.