Hi there,
Recognize the problem, there are so many great items on the STEX. It got a complete mess. I threw out all the plugins and started to use the pluginmanager. Very handy. Also, for the downloaded items I have a Simlib folder, my library of downloaded stuff. Like N-O-Body, I have organized the plugin folder. Saves you tons of time :-). Other: I am adding no more than two or three items per time. If it gets messy or it doesn't work well, you can easily trace it back.
Hope this helps,
Goodluck,