From what u`ve listed it sounds like u have a permatan. More than likely your neck can be evened out without even using a lightener, just exfoliation. A sample reg would be:
AM: Shower with Likas/Kojie San soap (or alternate between the two, I prefer Likas)
Apply a vitamin C serum
Apply a natural lightener such as Carotein/Sure White etc.
Apply a zinc based sunscreen (this is VERY important)
PM: Shower with Likas/Kojie San
Apply a DIY LA lotion or u can purchase Amlactin if u cant be bothered with the DIY route.
If ur only focusing on your neck area you can purchase an AHA cream instead. Walgreens has a cream that has worked really well for members here, Reviva Labs Glycolic cream is also another good option.
There are a couple of articles that show that RA (retin A) works well with GA. So a RA/GA combo is another option. Start at the lowest RA percentage and work your way up. Start with applying it twice a week then u can bumb up to every other day or so depending on ur skin`s tolerance.
I would also suggest weekly LA peels at 40% if you dont go the LA lotion route. When doing these peels put the kojie san and any other acids on pause for at least 24 hrs prior and after the peel.
There`s a member endt1 that got rid of his permatan through exfoliation alone, I cant remember the name of the thread but it had pretty helpful info. The peels sticky also has valuable info.
Umm I`m typing pretty fast so I hope I havent left anything out. If I have, members feel free to chime in. Anymore questions feel free to ask.