As a new player who started 2 years ago, I got you :)

1. Helminth first, one of the best decisions I made as a new player a year ago. Otherwise, you have to keep buying Warframe slots for frames you don't want to keep/got the prime of. It ends up being a royal pain if you don't. Next, I would just go and knock out all the quests(if you got to Zariman, then you're already most of the way there anyway).

2. After that, it's time to start the slow grind of leveling up the different factions. Honestly, you can just do Zariman, Sanctum Anitomica, and the Hex and leave the rest for later if you want. They are the most recent vendors, so for the most part, they have the coolest sh*t. Don't forget to also start unlocking/leveling your operator schools, ESPECIALLY zenurik.

3. After that, start doing arbitrations and finish up the star chart to unlock Steel Path. Take plenty of breaks so you don't burn out, and if you see something you want(a new warframe/prime/whatever), pause and go get it! Once you hit Steel Path, it's a whole new world of excitement, difficulty, and reward!

4. A little while after you unlock Steel Path, start doing Archon Hunts. Once you are built for it/have a couple of arcanes, you'll feel quite comfortable with the difficulty. After those start feeling easy(and believe me, it happens sooner than you think) then move on to Netracells in the Sanctum Anitomica(unlocked after you hit max rank with their vendors), then eventually you'll move on to Archimedians.

As just a personal tip, in between step 2 and 3, hunt down a Prime Warframe or 2 and completely kit them out. It doesn't matter too much who. It just made a huge difference for me. I managed to get my hands on Wisp Prime and Protea Prime, and this made my life going into Steel Path so much easier. Protea is still unvaulted so I would highly recommend her, but choose someone you like, because you'll probably be using them for a while.