Great guide Katie.
I'd also like to add one thing which could be a life saver assuming you have the right info:
Say you actually remembered that Solace made the thread. There is a nice feature in the upper right of the form (directly next to the "key word" part seen in pic 2 of Katie's post) in which you can enter a person's name (or part of it if you can't remember it exactly; just uncheck the checkmark if that's the case). Choose weather or not you're looking for threads Solace started, or just threads Solace posted in (again, we're assuming we remember Solace started it). Just using the keyword "robots" (searching titles only) and looking for threads Solace started, it narrows it down to 2 posts (and the thread that Katie was looking for is among them).
Just a handy search tip which has saved my life a few times. There are a few other things which can make life easier if you have the right info, but IMO, that's the easiest of them.