Well... the general guideline is that "para" indicates a consequence, and "por" a cause. For example: Te llamo por tu examen, para desearte suerte. (I'm calling you because of your exam, in order to wish you good luck). Of course there are many other uses, contexts, and exceptions, especially for "por", which is very frequent, but "para" tends to be used along those "consequence", "in order to", "so that", meanings.

Hola..para añadir a la conversación POR Se debe usar "por" en las siguientes ocasiones: -Para indicar acciones que se repiten: Voy a caminar 2 veces por semana -Cuando se cruza a través de algo: Cruzamos por el tunel, caminamos (por) debajo del arbol -Para expresar el motivo o causa de algo: Lo hice por que queria, la economia esta afectada por la inflación - Para indicar un lugar aproximado: Estamos situados por la estación del tren ( cerca de la estación del tren) -Para indicar intercambios o compras: He comprado este auto por 1000 euros PARA Se debe usar "para": -Expresar finalidad de algo: He comprado este regalo para ti -Fechas limites: El proyecto debe estar terminado para diciembre -Dirección final: Este año Viajaremos para la playa -Expresar puntos de vista u opiniones: Para muchas personas, la navidad es una epoca triste Espero haber sido de ayuda!! Hasta pronto

Here is how I teach my 2nd year students in high school. It leaves a lot out but it covers the essentials and is easy to remember: Por means: by, through, along, per and for. When choosing between PARA (for) and POR (for) use the following guidelines: Use POR when expressing: in exchange for; on behalf of; the duration of an action Use PARA for all other uses of "for" Te doy $10 por ese libro. (in exchange for) Hablé con ella por ti. (on your behalf) Hablamos por 2 horas (duration of time) Most other translations of "for" will use "para".

You are in luck. I stumbled upon this youtube video yesterday. It simplifies all the rules down to one drawing. https://youtu.be/8h1m6W4ZqgM.

I think it is a good question, not easy to answer, but I'll give you my thoughts: "Por" stands for cause and "Para" stands for purpose. "Por" is a short form of "por que" which means "because". So it will be better to use "por" when in a question/answer you just need/give the reason (more general). But you choose "Para" when in question/answer you need/give the purpose. "For" is translated as "por" and "para". But I think that "por" is the more often. "Por" equals only "for" "Para" equals "for" and "to" (When the use of "to" implies a purpose.) Hope I helped you