First though, you have to have a rough idea of the market you want to go into. Let's say you're into the offline stuff.
The BEST WSO you can buy is the one that seems to answer the questions you have at the moment - buy a MAXIMUM of 2 WSOs(not more!) on that particular topic.
Then put what you discover into action.
Even if you already know the stuff in there, just put it to action.
Even if you don't think it will work - put it to action.
Even if you can find the info for free elsewhere - just put it to action.
Then based on your experience refine what you've learnt and possibly buy more products in THAT SAME AREA. Then put it into action.
You'll start experiencing results - maybe not what you wanted but you'll be closer to success. And then one day, you'll find yourself in the big leagues.