What you are doing is basically all there is to earning observation exp. Except you don't get observation from looking and considering mobs so you can skip that part. Essentially some places are just not worth much observation exp even if there seems to be a lot to look at.

Somethings to keep in mind that I've notice is that your level can affect the observation exp you earn, that is some areas you can earn a lot at a low level but none at higher levels. I don't know if the converse is true. And this is just speculation based on my observation.

The way I collect it at low levels is to explore areas I am familiar with so I know the key words to look for. After awhile you will know what places are worth going through for observation exp and which ones you might as well skip. There is a number of areas you can go to sub level 10 that will give you over 1k observation exp each. To help with this try discussing right away after you explore an area so you can see if it was worth anything so you know to go there with future characters.