Old, young, first timer, or not. If you know basic tactics and endgames, there are two openings you should learn first.
Also, your comment about which are for White and which are for Black? SCREW THAT! You should be learning these two openings before any other, and should be able to play both from BOTH SIDES before you even think about going with any other opening.
They are the Ruy Lopez (The opening as a whole, not "The White Side" or "The Black Side", BOTH SIDES!) and the Queen's Gambit (again - both sides).
Now you are going to say "but what if they play something else like the French or Nimzo-Indian?" The answer is that it's not important right now. Not like they know opening theory at that level. I play experts that still don't know how to play a Queen's Gambit.
If you were (or are) an advanced-beginner or intermediate (or higher), and were going to really learn some opening lines and variations well for OTB tourneys (remember, no opening databases allowed like online), what opening(s) for White and for Black would you specialize in, and why? Maybe you are in the process of doing this now.
Assume your goal is to eventually become a Master. Please state which openings are for White and which are for Black. If you want, feel free to add in your lines and/or moves in diagrammatic format.
I'm not talking about someone starting from scratch who doesn't know tactics and basic opening principles.