OK, here's how I figure it (and I apologize for the impending crudeness).
You have three main values: pH (7.35-7.45), Bicarb/HCO3 (22-29), and Carbon Dioxide/CO2 (35-45).
If it's metabolic, the main consideration is HCO3. If it's respiratory, the main consideration is CO2.
So let's say you hold your breath. O2 transport is inhibited, which means that your CO2 rises. The whole point of respiration is to eliminate CO2. When CO2 goes up, that equals respiratory acidosis. A major risk factor of respiratory acidosis include hypoventilation, because your body is not blowing off enough carbon dioxide.
OK, metabolic acidosis is more fun. Let's say you have norovirus, and are suffering from epic diarrhea. A large amount of bicarb (HCO3) is in your gut. When it is gone, and your bicarb (which is an alkaloid) is diminished, you develop metabolic acidosis. I remember it as "out the ass, assidosis." Now, if it was the other way, and you were vomiting, you would lose your stomach's acidity, creating metabolic alkalosis.
Hope that helps.