To paraphrase the real estate business, the most important three things are: security, security, and security.
This will impact your selection of DBMS and its configuration, server configuration (SSL, etc.), application code that verifies user credentials, etc.
And the next three most important things are testing, verification, and validation.
Now perhaps since it is an "academic" project some of these things would not be as critical in terms of actual consequences as they would be in "real life" (loss of profits, lawsuits and so forth), but if your intention is to learn what would, in fact, need to be done in real life, then they would seem to me to be the things that require the most emphasis.
