Best Crystals:Meso Conversion

Hello I am new to the game (2nd week) but have quickly realized you need a ton of meso to progress your character to any meaningful level. If I need more meso to buy emblem equipment, and want to spend IRL money to expedite, what techniques yield the best conversion rate? (Staying within the rules of the game)

I dropped around 10K crystals ($60) into treasure boxes before reading that’s one of the worst ways to convert. I’ve made around $3.5B with what I’ve sold so far plus i still have 2 ancient armors, a few other mythic items to sell and endless legendary/unique equipment.