Can somebody give me advice on UI usability?

Can somebody give me advice on UI usability?

After explaining main game options for 14 minutes tutorial I understand that the UI must be changed (simplified and made more obvious).

This is the project:

https://sourceforge.net/projects/projecthelena/ (screenshots and video tutorial)

I'm going to completely redesign the interface and:

1. Drag-n-drop for items.

2. Change 'shift' and 'ctrl' for context menu (plus to make Android-friendly).

3. Reduce text information and make everything as graphic as possible.

But I'm quiet a noob in this question, so I may miss an important chung. What else should be done here? Maybe even to hide backpack, log, ground items, etc. into submenus...?