Content is the key and it wont be like most sites. Things like literature reviews, meta-analyses and so on. Collating data can work too if the data is widely scattered or hard to access. To build trust on your site for an edu link you should always quote and link to the source or primary literature and you should have your qualifications listed on the about page.
another way is to go to academic conferences and talk to people and let them know about your resource in your conversation. Just talking to them will often give you clues to what they are looking for. Just ask them whats missing or what resource would be valuable to them.