Rather than ask how long is a piece of string I was hoping that as a non-techie the community might give their top piece(s) of advice of do's and don'ts. Not just to recommend particular pieces of software but, for example, it might be about the business process (eg make sure you have appropriate metadata for your assets) or about being realistic about what any one piece of software might achieve. If you do recommend one system over another it would be helpful to know why.
My favorite piece of advice is "pick software LAST." I say this after seeing horrendous mismatches between what people thought software would do -- what they wanted it to do -- and what it actually did in practice.
Some things to do and questions to ask before you go software-hunting: