SoapUI I don’t remember that I wrote about it, it is one of those tools that we must master to do some quick tests. Very easy to install, even better to work on it.
I think the biggest tip is RTFM, as Suchakrapani once told, and it is here
Don’t forget the <?> WSDL at the end.
The tests are very data-driven, I think the second biggest suggestions is: read the logs.
If you take more than 5 min to do your tests, probably it’s somehow wrong or you haven’t done it correctly