Adding info_observer_point entities to your map is a good way to show off the visuals you're really proud of and gives the map a certain polish. However, orienting them just right can be a trial as there is no real visual way to do so within Hammer (that I know of) beyond tweaking the handles and hoping for the best. What I found I could do is first run my map in game and fly around in spectator mode. I move myself to the specific position and orient to the proper facing near all the areas I would like to place an info_observer, then use getpos in the console to dump my current position and orientation. Repeating this command for all the spots I'd like, I finally use condump to dump all this console information to a text file. I'm left with a list of points and orientations that I can then use to properly place and orient my cameras in Hammer. You can also use this method to test different fov settings which you could then carry over to the info_observer_point parameters.