Mistake #1: Sending out invites like it's nobody's business
First and foremost, LinkedIn isn't a platform to make friends. So sending out invites to people who aren't even remotely related to your work isn't going to add anything meaningful to you. Connections is a vanity metric—just because someone has more doesn't mean you need to go on adding people!
If you spend even half an hour looking for the right kind of people—even if they are few in number—you will end up building a good professional connection and God willing, you'll also get what you are looking for, whether business or a job. Also, LinkedIn has set a limit on invitations—you can only send 3000 invites to users. So be judicious.
Mistake #2: Not making the effort to write a personalized message
As we said earlier, LinkedIn isn't a place for those looking for friendship but to cultivate and grow serious professional relationships. When you are sending an invitation request to someone who you don't know directly, it makes sense to give your reasons behind wanting to connect with them.
The generic, by default message that LinkedIn has, will gain you no brownie points, in this case—the connection. So take the time to craft a personalized message, addressing the person you wish to connect with and explaining why you are reaching out to them.
Mistake #3: Not giving solid proofs of your expertise
This is especially an important point for those looking out for a job. Seasoned recruitment managers on LinkedIn will close your profile and move ahead as soon as they get a feeling that your claims about your expertise have no solid proof.
They are looking for real people with real talent and real skills—your profile will be the first to be filtered out due to either its incompleteness or because it comes across as all hat and no cattle. So back your claims by proofs. If you say you're a killer graphic designer—show your portfolio!
Mistake #4: Not being discreet and cutting straight to the chase
No one likes to lend their ears to marketing spiel. That also applies to the messages you send to your connections. Just like how in real life you will be cautious in asking for a job or business, you will also need to practice discretion on LinkedIn as well.
Just because you have connected with someone doesn't mean you hound them with questions and requests. Normally when people write a personalized note on the invitation request, the receiver usually answers—if yours hasn't, just ask them once politely on the message, if they don't reply to it—it's best to leave them alone.
Mistake #5: Not using a clear photo or no photo at all
People these days don't even accept friend requests from profiles with no photographs! Sometimes, people upload grainy or low-resolution pictures of themselves—which rules adversely to their interest.
In this day and age of smartphones, we don't think it will be any problem to get one decent photo of yours clicked. After all, if your profile clicks with a recruiter, it's you who will be benefiting from it.