The most common social media mistake brands make is using any means to get more fans for the fanpage. It is always good to have more fans but it is more important to have the right fans. The focus must always be on converting all customers to fans and all fans to customers. To achieve this – a combination of new likes, high engagement and special offerings is what the focus must be on.
Contests are a great way on engaging fans and bringing in new likes. But having too many contests with too little gap between them will attract the wrong kind of fans who hop from page to page trying to win contests but know nothing about your brand or will never purchase your products. Have up to 4 contests a month depending on the nature of your product or service.

We have talked about this before and we shall keep saying it. Be Social. If you only talk about yourself no one will be interested in you for long. Keep the content a healthy mix of social content and brand posts.
Social Media Ads are a great way to reach a specific demography. It gives you the most cost effective advertising option. You can reach out to audiences with all your specifications put in there. (Women between the age of 25-40 who love knitting, Desperate Housewives and Beauty products) There are different types of payment options as well and depending on your content you can either pay per click or pay per view.
Most content is inspired. Wherever possible credit must be given to the original content creator especially when using images from other sites. This can only help the brand page and the chances of the tagged or credited person sharing your content with other will be higher. And while others are sharing and liking your content it is important that you also like and share their content.
Hopefully these tips will help you on your way to avoid some common social media mistakes.