You can avoid using dialog boxes alltogether! In some programs there's a minibuffer that shows errors and warnings. Along that, it may also ask you a thing, where you must type what you want to do. It is quite clean and nice solution, I tend to prefer it over a menubar.
But if you really must use dialog boxes, try this:
- One sentence per dialog only
- At most two or three buttons
- Make the text readable inside the dialog (bigger, black-on-white)
- Rather use one dialog than many small repeatedly (tip: listbox)
What do I think about dialog boxes? In nutshell: They are dumb and stupid things. Programs that use them get on my way and slows me down with their stupid meaningless questions. Also, often programs that use dialog boxes are rather dumb.