I started learning Spanish 25 years ago and I’m pretty good (even if I say so myself). It was not continuous because I lost my Spanish mojo for about 3 years before resuming to learn. My Advice:-
1. Buy a Complete Spanish Course book (Teach Yourself with some easy CDs supplied). Take notes.
2. Take your time and don’t move to Chapter 2 until you fully understand Chapter 1.
3. Before you challenge Chapter 3, revise Chapters 1 + 2. And so on.
4. I bought Michel Thomas 8 CD Spanish Course just before I noticed it’s free on YouTube along with his Intermediate and Advanced CDs. No notes necessary, just listen repeatedly. They’re good and passive learning is very beneficial. Keep to your Complete Spanish textbook too.
5. Download the RNE app for radio (Radio Nacional de Espana) and you’ll have the main radio channels in Spain. Within that suite the presenters on Radio Clasica speak slower than the DJs and newsreaders on the other channels. All the radio channels are good for listening.
6. I continue to use Duolingo to keep improving my day to day Spanish. It’s free unless you want ad free etc.
7. When we are in Spain I inflict my Spanish on Spaniards because they want to speak English. They really want to learn English, this I cannot stress enough.
8. Years ago I took classes in Spain and found them fairly staid and generic.
9. These days I do much trekking in Spain with mixed nationalities including Spaniards and I exchange English and Spanish conversations.
10. I used to exchange spoken English for spoken Spanish lessons @ four hours per week, but that faded out. Spaniards tend to lack patience - that’s just a general comment earned by experiences.
Note:- It’s not easy to learn another language despite what you may be told. It takes time, discipline and effort. You can promote your enjoyment by listening to language CDs while you are driving etc. “The Language Tutor” on YouTube is excellent too for French and Spanish.