Can I share my papers openly after publication?
The degree to and the format in which you can (legally) share your papers openly, for example by uploading
The Sherpa/Romeo database catalogues policies by journal for many publishers.
If a publisher asks for a transfer of copyrights during the publication process, you may be able to negotiate a more favorable agreement. The SPARC Author Addendum provides a template that (among other things) allows the author to disseminate a typeset version of the article for non-commercial purposes.