I am a man solo traveler. On my other 4 solo trips to Europe, I stayed in hostels when available, the kind of place where solo travelers and sometimes groups of friends stay, to save money, where you share a room with strangers. For my trip to Spain in October, so far I have choosen all hotels. I have been using booking.com to find and reserve hostels and hotels. On booking.com, searching for "guesthouses" will show the low end hotels known as hostales. I don't use guidebooks to find hotels. I try to buy most of my food in grocery stores or markets. To me the only excuse to spend money on restaurant food would be if I was my family or friends and we had no other place to sit and talk and/or if ths weather was just too cold, rainy, or stormy to eat outside or if there was no cafe in a museum or lobby where I could sneak in eating food I had bought at a market or grocery store.
After Rick Steves, another good guidebook is "The rough guide to Spain", and possibly the "Lonely planet guide to Spain".