Hello Anna! This is a very complex subject, so I will try to be simple (I hope that can helps): "Pra" is the short form of "Para". So "pra mim" is the same thing as "para mim" (just remember that "pra" is the informal form and it should be used only in conversations). "Para mim" or "Pra mim" is usually translated as "for me" or "to me" in English. "Por mim" is usually translated as "by me". But there are a lot of exceptions. P.S.: You can read the English version of this article: http://lisantoss-portuguese.blogspot.com.br/2016/08/quando-usar-por-e-para-em-portugues.html

pra mim is the same para mim but pra is used only in conversation . in writing is used para mim. Para\pra mim is when someone give you something. - este presente é para mim (you receive a gift by someone= to me\for me). por mim is used when you do something and tell a someone you do it . Este livro foi escrito por mim (I write the book = by me).

Hi Anna! Para mim - To me (Formal way) Pra mim - Informal way, this is the same as You too --- U2... People "cut" this, people create new things with the words, here in Brazil we do the same. Por mim -- When we ask something we can use this: Você pode fazer isto POR MIM? (Could you do this FOR ME?) I also can use this in sentences where something was made for me, as Lucas told you. We just "cut" some words here in our daily life. Like in USA people do the same: For you, you wrote: For U. Or: ASAP ... (As soon as possible). We also do the same here with these words: Você ---- vc --- (You) Também --- Tbm --- (Also) Por que, porque, por quê e porquê --- Pq --- (Why/ Because) Beijo --- Bj --- (Kiss) - We use this online to say "bye". Daily we DON'T use for example: Eu ESTAVA (I was...) We USE: Eu tava. but this is just our way to speak. To write "TAVA" it's wrong. When you are writing something, you must write: ESTAVA.

Olá, Anna! Tudo bem? Para e pra são iguais, a diferença é que "pra" é mais usado em conversas informais, enquanto "para" é usado para conversas formais e para a escrita. :D

Sim, tanto o para como o pra são preposições. Nesse seu caso a diferença é que com o pra fica mais usual, informal. Já o por mim tem outro sentido.