How do you clean or gut fish
Here is a a basic video tutorial so you can see the basic steps. 

The biggest traps when cleaning fish is failing to remove all the guts, leaving bones in the filet, and not removing all the scales from the fish.  You can, if you choose, just gut the fish and cook whole stuffed with some aromatics, which can be really good. This guy will show you how. This works very well with smaller fish like trout assuming your guests are used to it.

So to avoid the pitfalls mentioned above, you need to make sure that the cavity of the fish is 
fully empty before you start the filet. You also want to run your hand over the outside of the fish after your rinse of the cavity to make sure that all scales are gone.  The best way to keep bones out is start at the spine and let the fishes rib cage guide your knife down and out.  If you want to remove the skin (not recommended for trout but other fish have much tougher skins), just put the filet skin-side down and slide your knife along at a ten degree angle.

Oh, and the most important thing? Use a filet knife that is super sharp, you definately don't want to tackle cleaning with out a sharp knife.