Testing is kind of the first step towards safer sex. Sort of a 'know before you go' thing. Then there is the birth control conversations, fluid bonding discussions (if wanted), and conversations about barriers, and specific sex acts (i.e. use condoms or other barriers for all sex, not just PIV but oral, anal, etc.), discuss the risks of how different infections are passed, the level of risk you want to take, the level of risk she wants to take, the level of risk you will tolerate in potential partners and so on.
Now's the time to research, don't get too freaked out (it's probably different than the last time you and she were on the market), and talk a lot explicitly about this stuff. Save yourselves some pain and worry along the way.
I have found the American Social Health Association very helpful - http://www.ashastd.org/
. The San Francisco city clinic - http://www.sfcityclinic.org/
- has lots of information organized so that you can read and absorb it quickly.