I'm just thinking out loud here and interested in your thoughts as well.

I have studied 20 languages now (in university classes). I enjoy it. But I'm aware that I don't think I'm particularly great at actually learning these languages. I can read in a handful well and others with some effort (basically any Germanic or Romance language at this point), and I can get by in a conversation in some. I've used Spanish the most, spending a lot of time in Ecuador, and now I feel confident enough to say that I speak Spanish-- I might even be close to "fluent", whatever that means. But it's still an active effort sometimes and I often don't have the right words to express what I want to say directly, or I misunderstand what someone is saying to me. And of course as a linguist I'm acutely aware of difficulties/mistakes, which is ok, but a bit of a challenge to stay motivated.

I've decided this year, while I'm campus and not traveling, I'd like to at least maintain my Spanish by using it some, and more than that I'd like to improve it. A few years ago I decided to forget all formal rules and just focus on speaking, which worked very well, but now I'd like to get back to speaking a little more standardly and with grammatical control, rather than just well enough to get by. I'm looking for a tutor at the moment on campus to at least practice with, but I'm not quite sure what exactly I want them to teach me.

So what are your thoughts on this kind of situation? There are few big mysterious of Spanish that can be revealed to me, yet I still am far from nativelike, so I have a lot to learn/practice.

I'm a tutor for English myself, so I feel like I should know the answer to this, but I've realized that most of my tutoring in those cases is with students who don't have a background in linguistics so explaining how English works (something I already mostly know for Spanish) is the key to their improvement with me, as well as of course just practicing and pointing out errors as I come across them.

I expect others here have encountered the same situation: you can pass a test easily enough, you can get by in a language, but you're not satisfied yet because you want to really feel like you command the language.

Of course I still enjoy studying languages/Spanish, but having the motivation to work on slowly improving is a bit of a challenge. I'd rather just relax and have a conversation with someone, but admittedly I don't do that often enough and I do better when there's a need to use the language, though during the academic year there aren't many of those opportunities.

(Once I work out Spanish, I'll try to get some of my other languages up to the same level, but I'm not in a hurry for that at the moment. I've never had a fully functional second language, so I'll be happy to start with Spanish for that.)

I appreciate that, Guijarro! At the moment I'm wondering how to work on it (most efficiently, or just in general). As I said, I'm just thinking out loud here, but would appreciate ideas from someone who has (or is in the process of) learning to speak a second language, while being a linguist (which is both an advantage and disadvantage, I think).

I think I agree completely [and in my case at least I don't yet need to consider questioning whether I'm a native speaker of Spanish-- definitely not there yet!]. But for a moment I'd like to step outside of the linguist role and see if I can reach the role of competent speaker, especially around at least several common genres rather than just reading linguistics papers and talking about traveling.

I don't think linguists are particularly better or worse at acquiring new languages per se, ...

Doesn't stop people from saying "oh, wow, you're so good at learning languages", just because I've taken a lot of them. I've learned to just smile and nod at this point, but I do wish I were "so good at learning languages". That would be useful! If anything, I'm just patient [not always-- learning again how to say various items of clothing, for example, drives me just a bit insane when I start a new language]

...but their inclination is to turn everything we encounter into a question of syntax.

Of course I often do that, but what's interesting about my situation with Spanish now is that over the last 3 years or so I successfully turned that off. Now I just speak Spanish, and in fact I sometimes feel behind when I'm trying to analyze it. I know that's actually a good thing, but I wouldn't mind bringing a bit of that back along with polishing how I speak it, while keeping up the fluency.