Hi emilxm,
English isn't my first language either and I know that sometimes my writing may contain misspelled words, but I'm always doing my best to speak and write correctly.
Sometimes I don't write words correctly, because I've seen them spelled wrong by other users
Even if I'd write them correctly I still feel uncertain all the time!
There are many ways to improve your English speaking skills : ebooks, online dictionaries (dictionary.com is one I use frequently)!