Most languages will at least have a couple of characters that don’t exist in your native language (like ‘ç’ in French or Portuguese). Add flashcards for the ones that are not obvious to you (front: the character and an example word, back: the pronunciation).
If your target language writing system is completely different (like the Russian or Greek alphabet, or Chinese or Japanese characters), you should decide now whether you want to be able to read and write in those languages, or just listen and speak. If your goal is fluency, learning the writing system is mandatory. If you’re going on a 2 week holiday, you’re better off skipping.
Especially for character-based languages, the complexity will be too big to learn it at once, so you have to break it down into more digestible pieces (in this case, the components/radicals that the characters are made up off). To learn how to do that, see Mnemonics.