It is totally dependent on level.
As a new player then killing a skeleton and getting a Cracked Staff that sells for 1pp would be pretty good going. At 40 it would be small change.
Part of the enjoyment is advancing to greater things.
One thing to note is that there is often a trade-off between interesting activities and money-making activities.
Once upon a time willowisps were an excellent way for low levels to make cash. I spent days of relatively boring wisp-killing to make some cash. Grouping in those days yielded relatively little at those levels except the odd bronze weapon worth 2pp. 10pp per Greater Lightstone was a fortune.
Now with the bazaar there are many ways to sell items to other players. Spider Silk is the most obvious and can run to 10pp per silk. Pelts (except ruined)also sell quite well.
Would really need to know more about your level/class to know what to suggest for you.
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Wherever I go - there I am.