I'm kind of new to website design. I read in a training manual that linking to quality authority sites from my landing page helps to stay in the good graces of Google, particularly Adwords. Is it okay to just pick any authority site that I choose and link to it or do I need to have permission from that site to do so? Thanks.
No need of any permission in general cases. But if they have a download page which can accessed only by paying a fixed amount and you know that direct link do not give them away. Asking always is a good thing because you get a chance to expose your site to the site owner. Pingbacks, trackbacks are often avoided by most webmasters