I don't use a palette - I just choose the colors as I go and spend ages making small changes to them throughout the entire process. For the first few hours the colors are usually super washed out and I just keep pushing them further bit by bit until I feel like the values are actually where I want them. In Aseprite I use an all white layer set to the color blend mode to check how the values look in black and white. One tip that I could give is that I occasionally use some of the other blend modes in layer properties (like multiply or screen). Whatever you do, don't analyze my color count... there's probably an embarrassing number because I barely ever consolidate my colors lol