As a rule, I try to practice decent grammar whenever I can, yet I'm somewhat laid back with others. It's up to the individual whether or not they decide to use proper grammar, but I do believe it gives a better impression of someone when they make the effort. However, I do get somewhat annoyed when establishments such as schools, hospitals, or government offices fail to use proper grammar, punctuation or spelling, etc. They really should know better... When learning a new language, though, I do believe grammar should take a back seat, so to speak. If you spend all your time trying to speak perfectly, you will no doubt lose all motivation, and give up before you are fluent. Plus, once you have learnt a certain amount, it will begin to come naturally; you will know when you say something "no, that doesn't sound right", at which point you can look up the grammar and perfect it. I think it's more important, when learning a new language, to simply make yourself understood. If your grammar is good enough that native speakers of the language can understand you, then you're doing well. There's no point boring yourself, learning every little rule, until you just don't feel like learning any more. It has to stay interesting...