okay! for me ... i will try to guess the meaning :D .. and most of the time this way fail.. like for examble و أجره العربه تصعد كالزئبق فى تموز i start to laugh :D ...then try to search on this word or the expression on the internet till find the appropriate meaning..

In my native language, English, it is pretty rare that I come across a word I don't know or can't figure out from the context. That usually happens when I receive an email from a Chinese friend and their dictionary gives them an obscure or archaic word. A little while ago I learned that "otiose" can mean futile or useless. But that is a C1+ word, and the person who sent it to me speaks English at about A2/B1. As far as "beguina", I thought of the Cole Porter song, "Begin the Beguine." (https://www.youtube.com/watch?v=iZ7ifstcOtQ&nohtml5=False) for a version by Sheryl Crow. The beguine is some kind of dance. But that is wrong. RAE says a "beguina" is a nun associated with los begardos, to obscure 13th-century French religious order.

It dependes how many times the word appears. First try to read and continue. If you can´t understand the rest of the tense, look it up in the dictionary. It hapens to me with english.

Well, it depends. Sometimes you can guess the meaning from the context, at least I try to get a general idea of what the text is saying. If I have no idea of what could the word mean then I try to look if up in the RAE (Real Academia Española), which is the reference dictionary in Spanish: every existing word should appear in it.

Well, you can always google it :) There are lots of words that are not widely used but they still exist. So you should just use Wikipedia or any other site, maybe the word you encountered is kind of archaic.