I was very unhappy with all solutions out there. therefore i developed my own management system specialized for web applications. The 1.1 version is just before release, so personally i would use my own system :D
If I would recommend another system it would be wordpress or drupal. The communities are bigger than from joomla. Documentation is a little bit better and the most users know these two systems.
Coding Suggestions are difficult. I do not know how professional you want to do your steempi
:-) ... And I do not know what your personally goal is. If you want to improve your coding skill, you can read coding standards like PSR-1 and PSR-4. In addition, composer installation routines would be quite helpful.
If you want to make your steempi more professional, you should think about modularization. Do you have a github repository? So i can keep an eye on it :-)