Is there a systematic approach to determining isomers in organic compounds?

[Xtreme]

Ok i don't really get how everyone forms isomers, in my class people just move carbons and other things to turn them into branches
Is there a specific way to determine the isomer of a compound without guesswork and counting to c if the hydrogens and carbons stay the same?

For example how would i find the isomers of
C5 H13 N

 

[Borek]

I am not aware of any systematic method.

 

[dantose]

There is no equation I'm aware of either.