There are several ways to get your way with the little woman. Depends a lot on the woman...they vary you know.
Never approach a woman with something she will consider "bad news" when she's not in a great mood. This, of course, may take quite a bit of time. Never hit 'em with a full frontal blow. Kinda sideswipe the issue on the first approach. You are planting a seed, not planting the tree....yet.
Next, you start the build-up for your purchase. You've got to make this car (it's always a car) sound like the greatest thing ever. A once in a lifetime opportunity (like the last one you bought). But, but, but, poor you will not be able to take advantage of this rare opportunity. Poor you. The next step is critical......time to stop....more later. It's cocktail hour!