40+ Tips To Grow your Linkedin Connections - infographic

Some key takeaways are:

Be more active on LinkedIn
Update your status daily and comment on updates from the companies you follow.
Send an invite for a new connection at least once a day, but make sure it is to someone you already know, or you can be introduced to the person through a connection you already have.
Participate in (or start) LinkedIn group discussions weekly.
Regularly update your profile information.

Make it personal
Instead of just sending a connection request, send a personal message with the request. This will make you stand out. Write a short message about how you know them, or why you would like to know them.

Reach out
Use the "Alumni" search feature to find connections from your high school and college. Join LinkedIn groups within your niche and take part in the conversations.
Though you can join 50 groups but focus on 3 -5 groups and stay active in each one.
Prominently display your contact information on your profile and clearly state your networking purpose.
Remember that LinkedIn is not like Twitter or Facebook, so when reaching out to people you should already have some sort of connection to them.

Ask people you know for endorsements
Follow up endorsements from others with a personal thank-you message. Don't accept or provide recommendations from people you do not know, or people whose skills you can't personally vouch for.

Double your LinkedIn Connections in just 5 minutes per day - infographic

image credit: Robert Libetti/ Business Insider