Avoid the Diamond necklace affair which ruined your reputation. Fight your way through french aristocracy to pass the financial reforms of King Louis (the husband, not current king). Economic reform. Avoid the famine as much as possible. If you can't you will have to give the people what they want and do a quasidemocratic monarchy.
If this story is to be accurate to history, your biggest enemy would be the aristocracy and the diamond necklace affair (which sank your reputation and cemented the image of a lavish debouchery). Prince Louis (currently not king yet) would be you biggest ally since he wanted economic reform but was blocked by the nobility, but stop him from doing free market mercantilism, because, as we all know, no regulation is as bad as total freedom.