Shower / bathe every day. Wear clean clothes. Brush your teeth at least twice a day. Those are basic hygiene things that should be done but many people just want to slather perfume or cologne all over and forget it won't help if you are not clean underneath.
I have realized that perfume doesn't work on me. As soon as I put it on, the scent just seems to disappear. I'm a girl, so I use a lotion that has a good scent to it. So I use that several times a day. It's a subtle scent; no one likes to be overpowered by your personal scent.
If you use perfume or cologne, remember there are many people that are sensitive to scents and can actually be allergic to it. So if you work in an office, apply this lightly so you're not setting off someone's allergies.