Love posting pictures on instagram? This is important for brand management and exposure. Get used to it or find someone to do it for you.
Twitter gives you a chance to make a statement (within the 280 character limit of course). Saying what's just right is important.
Don't use it as your company website, but a well managed Facebook page that links to your website is hugely important since Facebook is in a distant lead ahead of the competition when it comes to online referrals to company websites.
An often forgotten optimization gold mine is Google Maps. Most people searching for your business are going to be doing so from a mobile device. Get ahead of the mobile first campaign.