One thing I forgot to mention and it's very important. Do not install the LinkedIn app to your phone or any other device. The app will data mine your email contact list. After installing the app on my iPad, all of my wife's friends, business associates, literally anyone that she EVER emailed started showing up as "people you may know" for suggested contacts. Even our fourteen year old kid was listed...lol.
However, as bad as the above information is, you can actually upload and sync a contact list from nearly any source. Examples are Outlook, email accounts like Yahoo, address books etc.