I agree that it depends partly on how you learn - I am much more like to do well if I see things spelled, and if I write them.
It also depends what is available- face-to-face classes are usually best, but can be difficult to find these days. But we also have the Internet now, and it doesn't really matter where you are for online classes (timezones can matter, though.) My Welsh classes have just restarted this week. I like doing a class because of the other people in group work in particular.
Duolingo is not a total waste of time - I have been learning Dutch from scratch, but I bought a grammar book alongside, because Duolingo is generally rubbish at explaining grammar. I think if I hadn't already done German, I would be struggling a lot more with the grammar and sentence structures. It's difficult to explain separable verbs at the best of times, but Duo doesn't even try, it just shows you the pattern, and it took me ages to get my head round them, even when I had an actual teacher at evening classes.
Duolingo can be useful for vocab, it's good for patterns. I have been using it to revise my school and evening class languages.
But as well as Duolingo and online classes, there are resources available all round the world - videos, websites, etc, etc, so you can do a bit every day. Back in my school days, you had to find someone who was going to France and ask very nicely if they could bring you back a newspaper. Now, you just Google. That makes the options way easier.
In your situation, I'd look for an online class and do a bit of Duolingo and maybe another course or practice site online. I think you need to get to about high A2/B1 level before websites etc in the language aren't too impenetrable, as they often have more formal vocab/grammar.