Who is looking at your profile? It might just be your next employer, your current boss or a prospect.1. Don't ask for recommendations.
From people who don't know you, that is. Why would you expect someone without first hand knowledge of your expertise to say something great about you? I have gotten many requests like this and it always surprises me, and I never do it. Even worse: when it's sent out as a mass email...not cool.
2. You don't give back.
Great networking is based on giving, not receiving. Endorse another person's skills and you not only give them a virtual pat on the back, you may also help them show up in search results. Personally, I won't endorse anyone I don't feel comfortable endorsing, it's not genuine.
3. You've forgotten where you are.
LinkedIn is not Facebook. Most people use LinkedIn as a professional social media platform so always present yourself in a professional manner. Show off your vacation and party pics someplace else. When you want to leave comments, share material, etc., always assume a potential employer, employee, customer, vendor--anyone--is going to read it.