Everything can play in your cartoon. But remember to show their feelings.

Creating your main character.
Don't try to be Picasso. Your pictures should be comprehensible. Begin with something easy (make sure that when you draw it few times it still looks the same). Then add some details, colour it if you want to (coloured pictures are more temptating but it takes more time to finish them).

Stanley as an individual.

It will gets more interesting when your character obtain some features like: a) being workoholic b) hating parsleys c) dazzling smile

He lives on the planet Earth. And it means he meets a lot of people day by day. Create some and establish their relations.

Last advices.

the action should go fast

don't forget about good old jokes

and an impressing ending