I have a black niobium septum retainer for that very reason. At 12g, it's not very noticeable at all... Oh, and I have actually not yet run into problems with my tongue pierce, though I'm sure it's an eventuality. I removed it for interviews. Hard to hide once you get into single digits with those, too.
My 1/2 inch lobes are generally decorated with flat black horn plugs. Women can get away with solid plugs more easily because it's 'just an earring'. wear hollow ones and then more conservative folks go . I know.

Like you only 4 of my 10 are visible. My tattoo is invisible in normal work clothes.

Hygiene about piercings is absolutely important. Hence my organic plugs. Funk happens, but much less so with organics (bone, wood, horn...) and if you keep them clean and oiled, so much the better. Silicone (esp. the new implant grade ones from Kaos now) is very passable, too, but you should always remove it to give the fistula (yes, the insides of piercings are called that too) a chance to breathe. Skin is skin.

Oils vary in lubricity. I use vitamin E on my plugs and Lavender on a couple barbells, where a very light oil is necessary.

Happy piercings don't produce as much funk. Funk smells nasty and is one of those things that cannot be covered up. How does this tie in with Interview/Work etiquette? You had to ask, huh? I worked with a girl for a while, very nice, very sweet, had ear funk that I just could not stand... and tried to cover it up with perfume. Do not be that girl.