If you were to post a clear photo of the finish you can achieve at present, it might assist with diagnosis of the problem.
Cutter runout creates a scalloped appearance.
Conventional versus climb milling = poor versus good finish.
Wet cutting will produce a better finish. Continuous coolant during heavy cutting, or a spray film during light finish cutting helps.
Use a virgin tool that has not been used on other metals or for roughing. The tool should be sharp enough that it is dangerous to touch the cutting flutes. Uncoated is sharper because the coating tends to encapsulate the cutting edge which produces a radius over the cutting edge.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)