When/how to start contacting grad school professors?

<p>I am an engineering major and will be applyying for grad school this coming Fall. Most applications I see are due in december/january with some reviewing apps as early as october. </p>

<p>Is the summer a good time to start contacting or would Fall be better?</p>

<p>Do you guys have any tips on how to contact profs regarding working with them for grad school?</p>