Say it right first time
I'm putting a lot of money into Polish lessons so that I can do it right. I have to take private lessons -- when you've done a bit of language learning before, classes tend to go too slowly for you. There are so many concepts that I already understand that most English-speakers don't, so I'd just sit there, bored and miserable, as the teacher tried to explain grammatical gender or something basic like that.
I could, of course, learn off my own bat with a book. Why don't I do that? A copy of Teach Yourself Polish or Colloquial Polish, a Polish dictionary and a Polish reference grammar would all come in at the same price as half-a-dozen private lessons.
There is a mistake I commonly make in Gaelic: I drop the second n in urrainn. This is because I'm comfortable enough with the relationship between sounds and letters in Gaelic to write what I say. However, when I started learning to use the term, I wasn't. I learned the term from a book and used it at a conversation circle with a group of other adult learners. I learned the pronunciation wrong, and this has led to misspelling it. Now that I'm aware of this, I'm trying my best to change it, but changing is not just a matter of learning something new -- it means unlearning the mistake and it's really very difficult.
I'm taking Polish lessons because I know that, contrary to the beliefs of some teachers and learners, pronunciation is not a "minor detail" that can be "ironed out" at a later date. I couldn't learn the accent from a book -- I need a person there. My advice to all learners is not to worry too much about written details, but focus on the spoken. Language didn't begin on paper -- it began in people's mouths.