I've been through the Spanish tree and really struggle with three pervasive issues that make me frequently mess up translations (esp. when composing in Spanish). If any of these are explained somewhere I missed it. Appreciate any tips or mnemonics other people have to help sort it out... I know in time I'll have better instincts for all of them but I'm seeing a lot of "red" right now because of these even when I understand the meaning of a sentence.
When and where to put these pronouns like "lo," "le," etc.. For example when writing "She said it to me," I am not sure whether I need: me, lo, which to put first, etc.
When and what linking words to use after verbs like a, de, por, para, e.g. It is definitely a mistake to associate each with an English word (like "a = to, de = of") because that leads to wrong answers.
When to use a definite article like "el" or "la" in Spanish sentences where the English doesn't use one, like "I like fruit," could be "me gustan frustas," or "me gustan las frustas," I'm not sure which but there are enough definite articles where English doesn't have them to keep me baffled.