If you want, tell me your exact model number (from Settings → About phone) and the Android version you want (stock-like vs highly customizable) and I’ll recommend the best specific ROM build and link the most reliable threads.
Here are some of the top custom ROMs available for the Samsung Galaxy A8 Star: samsung a8 star custom rom top
This is a mandatory first step to allow the installation of unofficial firmware. If you want, tell me your exact model
Project Elixir markets itself as a "luxury" ROM. It takes the stability of LineageOS and adds the visual flair of crDroid. If you want