Both Facebook and Twitter

Hashtags

Limit hashtags to no more than three per post. Use relevant hashtags that relate to your post's theme or topic.
Don't hashtag #IREX or #IREXintl.
Use a hashtag tracker such as Keyhole, Hashtagify, or Hashtracking.

Images

Include a high-quality picture or graphic when available.
Pull images from Creative Commons if necessary.
Refer to the "Social Media Image Sizes Cheat Sheet" for specific dimensions.

Frequency

Post at least once per day to keep the account relevant.
Create a weekly social media plan to help you schedule posts.
Use a post scheduling platform like Hootsuite, Tweetdeck, or Buffer to preschedule content. Facebook has a built-in scheduling tool as well.
If you "pin" a tweet or post, make sure to unpin it when it is no longer relevant.

Audience

Who are you trying to reach and why?
What platform is best to reach them on?