Dr. Black posted this on his blog awhile back, but I wanted to share it with people who may not frequent his blog.
The title of the post is "How to Master a Foreign Language." The last line is a great summation of the advice offered in the article..."Friend, do not be afraid to make mistakes. Do not fear correction. Swallow your pride and speak out!"
There are times when I catch myself not wanting to speak in Greek class. Either I can't remember how to conjugate something, or I worry that I'll get lost in the middle of a long word. I've done two summer missions trips to Guatemala and most of my friends speak Spanish (which they learned either in High school and/or the university), so I used to have a tendency to say -τε as "tay", like you would in Spanish. I've found this is a common thing among most of the people in my first year Greek class who have any background whatsoever in Spanish. Dr. Black's advice is invaluable...you just have to suck it up, say some words incorrectly, and continue to learn.