For dyes you get a few just playing through the game, Black Lion Chests are where they typically come from. You can buy dyes on the trading post as well.
For gold the fun way to get gold is with the map metas, Auric Basin is my haunt. When it's fun and challenging it feels less like work, thus reducing your chances of getting burnt out on the game.
Sell unopened gear and bags on the trading post for the most optimal profit. The drawback with my method it that it will be slower, there are faster methods but they take the fun out of the game, IMO.