Well although I haven't come around learning spanish yet but out of the 5 languages that are the staple for europe sp,it,fr,ge,eng only german is probably a real pain to learn (I'm saying this from the perspective of a german native speaker that thaught it in some exchange language programs for a while).
If you have already experience in getting fluent in some other foreign language that's going to be a huge help, because in that case try to reflect what the most effective methods were for you personally.
As for the things in general that are going to help you. Get anki for vocabulary. Try to build yourself a spanish enviroment that you can feed of on.
Don't bother learning grammar until you're really interested in it (like when you've recognized some patterns in the language and want to comfirm their rules or sth.). Since speaking is your focus try to get a base minimum of vocabulary and a feeling for easy grammer for short sentences. If you're at that level maybe try to get some native speaking contacts (although this is something that probably a little far off).
Never ever feel obliged to do a certain amount of spanish every day but rather try to feel obliged to do some spanish every day. It's better to learn only a single new word and keeping the rut going than breaking it because you don't feel like you can fullfill a quota on the amount you have to do every day.
Really the most important thing is to try to keep your interest alive. Try getting textes about things that you're interested in and read them regardless of how much you understand, you don't have to translate those completely just pick words that you're curious about. Try to get interested in spanish music/audio material or try to find spanish dubbed stuff. Spanish dubbed movies with spanish subtitles are going to be one of you're greatest weapons for tackling listening comprehension.
The old Disney movies are always a great start for something like that.
Not going to lie getting fluent in a language is a huge time commitment it's not really hard but especially if you're busy with other studies you have to be smart about making sure that you have maximum uptime of language immersion. Like I mentioned music or dubbed stuff is great you can always listen to stuff like that in the background almost 24/7.
I'm basing this advice all off after failing through language classes(english/french) and their horrible teaching methods for years and using these methods with the main motivator of being able to enjoy stuff in these languages I've got top marks in both off them in a matter of 2 years each (that said I only focus on one language at a time).
I think the hardest thing when trying to master a language even if you really enjoy learning it are the stretches where you don't have a feeling that you're improving and keeping your interest up during those. But getting fluent is a really subtle thing much different from math where it clicks your ability will to speak will improve very stealthily.