The proper way to get what you want is called colour sanding and you need to use a 1200 grade wet and dry paper with a good sanding block, you flatten it until it perfectly flat and dull then polish it using a proper polishing machine and start with G3 then G10 polishing compund finish with a machine polish then hand wax.
its quite a daunting process the first time but will give a better finish than any high cost paint job, I used to do it for a living manay years ago, very satisying and you can get a real mirror finish flatter than any wet finish.
For a few hundred pound you can buy a decent starter kit
Cheers Ian