To this day I am somewhat amazed that they never told me as a seminarian that I ought to wash my hands before mass. Hopefully the seminary has corrected that omission by now. As least I have; to my shame it didn't even occur to me until several years into my ministry that this was more than a mere matter of personal hygiene. Don't ask me why. I'm slow, I'm thick, I take awhile to learn things, whatever. I certainly should have known better.
But since I didn't, I'll wager there are others who don't either.
So let's just get this little matter out there for all celebrants or would-be celebrants to know.
First: wash you hands before mass.
Second: wash your hands before consecrating the elements (that's called the lavabo, and is done over a lavabo-bowl while the 26th psalm is said privately, as the last step of altar preparation during the mass).
Third: wash your hands after the distribution (i.e., take the ablutions).
Why, you ask?
The answer is so simple people miss it all the time. It's the body of Christ we're dealing with here.
So, before the consecration and distribution, washing is done in order to insure that the elements being received are, and are seen to be, pure of any imperfections, dirt, etc.
Afterwards, washing is done in order that any fragments which may remain on the celebrant's fingers may be properly consumed. The ablutions (the last of the washings listed above) are taken by rinsing the thumbs and forefingers into the chalice and then drinking that water.
Of course, much of this is ceremonial in nature; nevertheless it is real. The matter of handling the body of Christ is something to which we tend with utmost seriousness.
Anyone who does not really believe "this is my body" may, of course, ignore these rubrics altogether.