LE or STDS? I've been involved in the hobby only twice before and never did anything without a cover.

Being a rather new hobbyist, I can tell you I would be much more worried about LE.  LE is a real possibility, whereas STDs shouldn't be much risk if the right precautions are taken.  So, if you're talking numbers, you have a far greater chance of getting arrested.  If you're talking severity, well I'd rather get arrested than get HIV.