I really, really like Step By Step in Esperanto by Montagu Butler. It's the best introductory textbook of any language that I've read. It's composed of maybe ~1000 or so very short lessons (each is about a paragraph), so it makes it very easy to make a little progress every day even if you only have a couple of minutes before bed. There's a nice mix of reading, translation exercises, pronunciation exercises, and grammar.

Find a local Esperanto group and go to their meetings. We're all pretty welcoming and most will be glad to help you boost your conversational skills.

Also, if you are in the States (or not), check out NASK (Nord-Amerika Somera Kurso). It is a week-long course which takes place across July 4th weekend each year, currently in North Carolina. That is how I built the bulk of my ability. I highly recommend it.

http://bertilow.com/pmeg/ is a great post-Duolingo thing to read through if you like reading dense reference grammars (as I do :)

There's lots of easy fiction literature; gerda malaperis, la eta princo, etc.

Nowadays there's a good amount of vlog content to watch. Evildea has tons, (https://www.youtube.com/watch?v=EYs_6gTE3O8 has a bunch of fairly ordinary casual conversation between people in it) and I also like https://www.youtube.com/channel/UCZLuNvGx99zmlEQL0oR_uvg

Finish the duolingo tree, then go to a multi-day congress asap, ideally the week-long UK or IJK, for immersion. Facile!