kermeo, I don't think you should be afraid of trying for one minute! Every one of those classical engineers who understands the theory and practice started with no experience. :) And I have at least two fader-pushing friends who can record anything - classical, jazz, rock, whatever - and make it sound great AND also mix incredibly well - including one guy who mixed half the albums in the '80s and is still going strong. They aren't tonemeister types, they're engineers who started as musicians and learned after talking their way into jobs. There were no audio engineering classes when they went to college. As a matter of fact, the other friend I'm thinking of now runs a university program!
This is music. No one gets hurt if you make pants of it, as the Brits say.
The thing about miking classical singers is that unlike "pop" vox, the room is part of the sound. So you don't normally want to get too close. My suggestion is to get the best flat mics you can (as opposed to character mics with an opinion) and stick one about three feet away and then another one or possibly two farther back to pick up the room. Where the room mics go is a matter of taste; use your ears to find where it sounds best. You could use more mics, but there's a point at which it becomes a hassle and you start having to worry about phase problems. If you have a small-diaphragm mic and a large-diaphragm one, use the large one for the room and the small one as the spot mic - the one close to the singer.
To avoid phase problems there's an old adage called the 3:1 rule: when you're using two mics on the same source, the second mic should be at least 3x the distance the other one is from the source. That rule is violated all the time, but it's a good starting point.
The main thing is to try and make a short test recording before the actual performance so that you can listen to how it sounds and make adjustments. Trust your ears.