but in practical terms, the activities you describe are fairly safe.

You can get infected by just about anything, at any time in this hobby... but chances are slim to none with the activities you describe.
Here... read up... suggest you also start to read postings on "The Erotic Highway" board where topics like STDs come up all of the time... Love Goddess is your guide there, she is nothing short of fantastic.

be infected with a disfiguring disease that will have you covered in open, festering, malodorous boils or simply corrupt into necrotic flesh that falls from your bones just by picking up the germ tainted receiver of a public phone.

go to www.medhelp.org and follow the links to the STD section. It is moderated by a doctor who also happens to run an std clinic. By far the best site I have come across on this topic.