The best way to keep the system clean?

[ronggui]

My problem, many times I install some software from ports, it install
the dependency software. Then after some time, I find that software
isn't what I want, and deinstall it. At this point, the dependency
software isn't necessary as well. Is there a way to clean them
automatically, like the apt-get autoremove in the Ubuntu system.

And the related general question is, what's the best way to keep my
system clean? Thanks.

-- 
Ronggui Huang

Department of Sociology, Fudan University, Shanghai, China

Department of Public and Social Administration, CityU, HK