It's no problem if you follow these commands
 
 Do the following to keep your system up-to-date and rock solide:

emerge sync #(if you have esearch installed consider using esync)
emerge -uDav world
emerge -av depclean
revdep-rebuild
etc-update #(or dispatch-conf or cfg-update)

Run this commandset once a week or how often you want. But I think once a week is okay.

If you are concerned about your securety run this command every day

glsa-check -f all

Note that it is still in developement (http://www.gentoo.org/proj/en/portage/glsa-integration.xml)

Unmerging packages with its depending packages:

emerge --pretend --unmerge PACKAGENAME `equery depends PACKAGENAME | grep --invert-match Searching`

emerge -uDN world || until emerge --resume --skipfirst ; do emerge --resume --skipfirst ; done