I lived and worked in Spain illegally without any problems whatsoever. It’s impossible to find any good information online about this. Why? Because who is stupid enough to publicly admit they did something illegal? ME. I taught at two different private language academies and was paid in cash. I had a Spanish bank account, health insurance, etc. all with my expired tourist visa.
I traveled to a different country every month. Let me introduce: Schengen. A treaty created between 26 European countries that eliminates passport checks. If there are countries you want to see outside of the Schengen, do it within your first 3 months. If you want to be able to leave the Schengen zone, then yes, get a student visa.
Truth be told, the night before every trip, my flatmates and I would stress eat Oreo’s and freak out over the thought of being deported back to America. I don’t regret my decision to live and work there illegally. However, I caused myself A LOT of unnecessary worry that I was going to get kicked out, fined and banned from Europe forever. THIS CAN HAPPEN. I am very fortunate that I was not one of these people.