Giving a great blowjob is a quality that men look for in women, but you want to be able to do it all the time without the fear of risking your health.
Whether you know your partner really well, or it is a spur of the moment thing, hygiene is the number one concern. Penis doubles as a reproductive and waste disposal organ, and naturally men like to keep it as clean as possible. But there is still a lot to be considered when it comes to having a man's penis in your mouth.
First, you should avoid engaging in oral sex at least two hours after you have brushed your teeth. There are many medical reasons for it but most of them are focused on the fact that you always have a bit of a gum bleed doing it. Exposing gums to any kind of bacterial environment is not recommended.
Let's consider the aftermath of the blowjob. It is best to use antibacterial mouthwash right after the fact. I know it sounds a bit odd especially if oral sex was just a foreplay, but for your own safety, sooner the better. There are many products designed especially for this purpose and you can find them in a form of a spray or gel as well. Peridex or Paroex will do just fine and there are also Listerine, Sacavol, Corsodyl and many others.
Oral sex is never about using your mouth alone, of course, you use your hands a lot in the process. As much as you would like your partner to wash his hands prior to approaching your genitalia, men like that too. The precum can contain a lot of different bacteria that can stay on your hands for a while. Consider washing your hands after the blowjob or at least use an antibacterial wet tissue.
While you are up close, check out if there is any abnormal secretion from the penis that has a strange color. That is most likely a sign that something is wrong. Any kind of secretion other than precum and sperm itself might be a sign of bacteria that was not supposed to be there. They can also have a particular smell that could signal a warning. Also, look for pimples or any injuries or wounds on the penis. Be warned that all of those probably have root in some kind of a bacterial problem. Any of these can cause problems to your health so make sure you address those issues.
Men like women who pay attention to details, especially when it comes to hygiene. If you are in a committed relationship, these tips will probably be a key point to help you stay in one.