Depends on if your looking for a fast fix / cover up or making sure its solid for years. Any place you have rust should be taken down to bare metal. Prep with a rust preventative and then paint to match. Most paint shops have a hand held unit that matches the color paint and even if your is faded should be fine. People worry all the time that the older paint can not be matched, but remember after a year your hood and lower rockers no longer match because they fade different. Its all about blending and what you think its worth investing to fix now rather then later.