A decent bolognase sauce should start with diced onions, carrots and celery. Also, add some wine (either white or red, personally i prefer a dry white) after you've browned your mince to deglaze. For the cooking time, the longer the better, you can cook it for hours if you like if you cover it on a low heat. Also, when you get towards the end, it's a good idea to balance the flavours to make sure everything is ok - i add a couple of drops (and i mean drops) of sherry vinegar if the sauce is a bit fatty, and you can also beat in some butter to make it richer.
Also don't forget the golden ratio of pasta - 1 litre water, 100g pasta, 10g salt in water per person. You need either a really big pot of water to cook pasta for 6 people or multiple pots otherwise you end up with a starchy gooey mess.
And one last thing about olive oil - whatever you do, don't use good olive oil for cooking, it's a waste. Just use some cheap light stuff.