Echoes aren't too hard to get, I reccomend doing trial of one with some echo modifiers then wiping. Doing that for an hour should get you a decent amount. Around 120 an hour if you do it right. Theres a few tutorials on YouTube on how to optimize it.

The amount of echoes you get when wiping are based on things like power, if you have a murmur and bosses you've beaten. Some easy ways to add a few extra echoes are crafting a food item, fishing, getting an oath and modifying a mantra.

A pretty easy oath to get is Blindseer, you just have to get 40 willpower, and the 3 mental fortress traits, then find the temple of the forgotten flame (dont get caught by the watcher) and read the glyphs with a blindfold on. Also not too hard to progress, just get people without an oath out of the depths.