Since you are wondering about the route, I assume you have not done a lot of reseach. The Forum's shop offer a number of good guides, like the one by John
Brierly.
But before buying a guide you need to decide on a route. For that visit the Eroski, Gronze and/or Mundicamino websites. You will see there are a number of routes, but the most famous, and travelled, is the
Camino Frances.
These web sites, just like guidebooks, suggest daily stages, and give information on elevation and albergues. Some albergues have kitchens (more or less well equiped). If you share grocery shopping with others this can help keep your cost down. Otherwise I find you pay almost as much that you would in a restaurant, and end up leaving food behind.
An albergue will cost begween 6-12€, pilgrim dinner 10€. Breakfast 3, and a sandwich and a drink for lunch 5€.
There are also albergues which as refered to as "donativos". That means you give what you can, what you think is fair. It does not mean free as they really need this money to buy food for those coming after you, to turn the heating on, to keep the albergue clean.
Start there. I'm sure the websites above will keep you busy for a while.