SharePoint can do almost anything, but…

• Remember to say, “That’s phase 2”. Keep a running list of nice-to-haves.  Evaluate and prioritize them after successful completion of the first phase. Don’t move your goal posts, especially for something that you might not think is that important after you have a little perspective.
• Avoid time-consuming customizations for marginally better usability. Do you really need the gnome graphic to smile every time you like a post?
• Don’t over-customize to the point that upgrading is impossible. Assume that to some degree, you’ll need to rebuild every custom (code based) solution you create every time a new version of SharePoint comes out.
• Don’t build a custom solution for something that SharePoint does out-of-the-box.
• Clean up your mess. Archive or delete content, sub-sites, pages, and web parts, which you no longer need or it will clutter up your site.
• Be clear on what you’re doing, what success looks like, when it is needed, how it will be done, and why it’s important.

ShareGate’s blog, which is just truly excellent, recently published a list of 10 things every SharePoint user should know. You should read that too.