The unsure -- "I think..."
Last week, I had received a call from a sales person who started off the conversation with, "I think my services might be a good fit for your company." "Really?" I replied. "You mean you don't know? Then why did you call me?" If you can't speak with conviction when you're talking to potential clients, then why would they ever want to buy your goods and/or services? I've never walked in a store where the salesperson says, "I think we might be able to help you."
There is a slight difference in saying, "I think" and "I believe" or even asking a question, "Hi, how are you and how can I help you?" The words you choose have a profound effect on how your message is received." The words "think" and "might" run the risk of you sounding unsure or insecure. Conversely, "I believe" conveys passion and is more assertive.
The wimp --"I'll try"
Imagine that you ask your friend to drive you to an important appointment and she replies, "OK, I'll try, but I can't guarantee that I'll get you there safely." When you tell a colleague and/or your boss that "you'll try," you don't leave them feeling confident about your abilities to get the job done. It's a little change -- "I will" from "I'll try" -- but it speaks volumes about you and your can do attitude.
The bully -- "He's a jerk," or "She's lazy," or "I hate this company"
There is nothing worse than a name caller, and I can guarantee no faster way to get to the unemployment line. You also sound like a juvenile school-yard bully. Avoid making unkind, judgmental statements that will inevitably reflect poorly on you.