My preferred approach is to get a foundation of the language, and then to practice it as much as possible by speaking, reading and looking up things I don't know.
At first, I would try to do an introductory course and find out how the language works. There is a range of resources I would use at this stage:
Personally I prefer audio courses. My most liked courses are available through the Michel Thomas method, or, for free, through Language Transfer. However, if I can't find one there, Pimsleur can also be acceptable, and I even worked on a text-based website with similar free courses once, called IKLL.
Sometimes, I would complement instruction with more visual and interactive materials. For example, for doing exercises and reading up, Lingualift, Duolingo, and Lingvist are potentially good choices.
If I need even deeper insight, I would try language learning books: Colloquial and Teach Yourself are the best series I've found.
Once I acquire more of an understanding, I would try using the language. This consists of many things:
Use on the street. I would ask questions on streets, order food, try to engage in longer conversations whenever possible. For this, a phrasebook is helpful (in fact, Language Hacking phrasebooks seem like a choice well suited to the digital nomad lifestyle). I would also install a mobile dictionary, and, after or even during each conversation, look up the bits I did not know how to say. I would also look up things I see on the streets but don't understand: street signs, shop names, words in advertisements, etc. Finally, as I discovered getting the conjugations right is a tricky part in language learning, I made a website called Cooljugator where one can look up conjugations in over 40 languages.
Look for a language exchange or perhaps even hire a tutor. Language exchanges now exist in almost any town, and can be found by simply googling. A popular type of exchange is called tandem. However, if not in one place for a long time, then hiring a VoIP tutor can be a great option: and Preply is a website I would recommend for that.
Read. I would pick simple books that you would like to read, and have a crack at them. Bilingual books can also be very helpful. In fact, my own startup Interlinear Books has been helping people with just that by subtitling fascinating books, and thus making them accessible for language learners.
In my experience, if you do these things and really work on a language, you can begin speaking it in just weeks, and gain an acceptable level in a matter of months. Moreover, the more languages you learn, the easier it gets.