Are you looking to recruit new supporters, reach existing supporters, spread your message? Different goals have different methods.
Also you’ll need to consider your timing. Some options can be rolled out faster than others, so make sure your plans allow for enough time. Email list buys may take a week or longer to collect the promised amount of email addresses. Google or Facebook ads may need a day or more to get through the ad approval process on Google/Facebook’s end, Twitter will often go through faster but it’s not instant.
http://www.huffingtonpost.com/laura-packard/how-your-nonprofit-can-us_b_6731854.html