building a release: branching or tagging

[Edward Dunkle]

please excuse if this is a double post.  It seems earlier posts have failed.

What is the recommneded practise for building an incremental release without
pulling  in incomplete code changes in the main trunk?

Some have suggested that we never branch and merge but simply tag individual
files associated with each implemented change to be included in the next
release so that each of these may be pulled specifically.  Do you see any
issues with this approach?

The docs seem to describe branching and merging as an approach to use.  Are
people successful with this?  

DO you make releases off a branch and then merge it into the trunk and then
make another branch for the next release?  

Do you make one branch for each release or branch and merge for each change
request that is to be included in the next release?

Thanks,
Ed