Well, first o all I have to start by saying a thing:t raditional recipes are not sculpted in the rock one time and forever. Ragù alla bolognese is a traditional recipe, as everyone of us well know, traditional recipes have a lot of variation, not only cause every famimily usually has it's own version, but even cause often you can variate your own version according to the ingredients you have at home in that moment or simply to try something new.
The version I'm going to give you is the basic version, feel free to explore new variation by yourself, according to your personal taste and the ingredients you can easily find.
This recipe has a quite long preparation, so usually we prepare a generous quantitity we stock in the refrigeretar divided in small portions.
Ingredients:
butter;
extra virgin olive oil;
a medium yellow onion;
a carot;
half a stick of celery;
60% of freshly grounded not too fat pork meat;
40% pf freshly grounded beef;
salt;
pepper;
wite wine (such as pignoletto dell'Emilia, but you can also use a pinot, or a chardonay or some prosecco);
plane tomatoes sauce;
milk;
1)mix in a large bowl the meat with salt, pepper, and a glass of white wine, let rest covered with a dishcloth for 10 to 15 minutes.
2) mince the vegetables, put them in a large pot (large enough to contain all the ingredients, better a terraccotta or a heavybottom one, cause the preparation need a long, very low heat simmering) with the oil and butter, turn on the heat and gentle sautè the vegs.
3)when the vegs will be properly sauteed, add the meat , stir well to let the meet evenly and lightly browning, meat will start releasing his moisture. The meat grains should stay separate one from the other.
4) when the meat will be evenly lighly cooked, add the wine, as much as you think necessary to give enough moisture preventing the meat on the bottom to burn and to distribute evenly the heat to the upper meat. let simmer for at list a couple of hours, stiring now and then and adding some wine or vegs or meat stock if necessary.
5)after a couple of hours, add the tomatoes sauce (personaly i don't add too much sauce and you can always add some more later if you change your mind, so better proceding for steps). Go on simmering for at list one more hour, stiring and checking if there's enough liquid.
6)if at the end you find the sauce still too much liquid, let it simmer without the lid till the excess of water evaporate (remember that when you switch of the heat source, the meat will absorb part of the remaining moisture, so don't let the sauce dry too much).
7)before use the sauce on the pasta (better kind of pasta for this sauce are tagliatelle all'uovo, you can easily make your own at home) add some milk and let it reduce warmig up the sauce (even when you pick some out of the refrigeretor)
This ragù is even great preparing lasagne alla bolognese.
I apologize for my poor english, however i hope i've been clear enough to explain you properly.
Enjoy and let me know!

))
P.S. some variations, include sousages or liver in the meat mix....