[Update: These ideas apply to Web pages as well.]
A few suggestions from a mere user:
-Stop using script-based popup menus. Go back to old-style Microsoft-standard (c. 2003) clickable nested menus emanating from a static menu bar, with standard headings (FILE, EDIT, etc.) plus the unique headings needed for each piece of software. If you are using script menus as a workaround for complexity you should redesign your user interface. If you are using script menus for any other reason you should stop.
-Knock it off with the icons. Use text buttons instead. The point of software it to economize on human effort, not to appear stylish. A trash-can icon is probably OK, but much more than that and users are forced to waste time mouse-hovering over your icons or (worse) looking things up in the online help.
-Hire focus groups of 75-85 year-old occasional computer users and turn them loose on your products. They may not understand the fine points but they will tell you quickly if your products have any gross UI deficiencies that people like you who use software all day may be overlooking.
-Use large-enough default fonts and buttons. You can always make everything resizeable for users who want smaller.
-Any command that does something major and irreversible, such as deleting a database, and that isn’t likely to be used often, should be on its own menu, or away from the other buttons on a page, and should require many clicks and, if practicable, the entry of a password.
-Standardize what happens after the user clicks a command. If you require a password to access the database you should require a password to delete the database. If you use “are you sure” dialogs you should use them consistently. No surprises.
-Minimize clicks. Someone told me he had to click five times to shut down Windows 8. Why?
-Stop changing user interfaces without strong reasons. Updating the style is not a strong reason. Tool makers do not change the designs of hammers or wrenches from year to year. There is a reason for this and it mostly applies to software, which is another kind of tool, as well.