i have already used the following process on my corolla 1998 green, (profile photo). u can use this process with out the help of any painter.
1) check ur color code,
2) then go to any color plant, and make that 2k color about half pond. cost about Rs. 300.
3) apply that paint on scratches with the help of any needle or paper pin , or any other sharp thing, but Don Not use QALAM, because smallest qalam is also very big against ur scratches.
4) after 24 hours, Use 2500 grit paper, and apply upon that scratchs for cutting.
5) and at last use "2K cutting cream" on that area with full strength, to buff this area. for SHINE.
Thats all. (for practical video, u may check youtube)