I’m fairly new to Warframe, only MR 6 with a few weapons maxed (and sold) and just now making Rhino as my first new frame. I have been working through the star chart and completing quests as I got them.
In my adventures I have encountered some opportunities to grind for certain things. Reputations with the syndicates, rewards from Fortuna or the the happy family in Deimos, or that frame you can buy from Duviri wyrm kills etcetera. But how do I know what is worth going for?
I don’t necessarily want to rush to end game ASAP, but I also don’t want to spend time grinding for something that I would very quickly replace anyway
You’re already getting Rhino, which I consider to be the closest to a “must have” a new player should aim for, as far as survivability go. In regards to other frames and weapons go, if you have the time to grind one whenever a new Assassination unlocks, go for it. Don’t need to be all at once, sometimes the RNG is cruel, but make a note of any that you skip. You’ll probably want to avoid the really annoying grinds, like Trinity, Equinox or Protea; thankfully they all have Prime versions now, but even that will be a matter of time.
You may also do some Nightmare missions, or crack Relics (if you’re earning them, of course), weekly Ayatan or Clem, etc.
For Syndicates, try to not overdo yourself, they can feel a little too much. From the basic ones, pick one of the sides (there’s three on the left and three on the right) which will all synergize with each other, and just do basic missions while having a Pledge. For all the bounty-related groups, pick one or two and do a few missions when you’re able. If that’s too much for a single day, just pick one and go at your own pace.
As you climb through MR, check the Market for new blueprints unlocks. At MR6 you should have access to the Kohm, the Hek and the Atomos, which are all fairly great new player weapons. If you’re in a clan, check out for the Ignis Wraith as well.
And when you find a couple of weapons that feel comfortable, try to level up the ones that aren’t so good to earn a little MR along the way. Put either your favorite primary or secondary, and then equip level 0 weapons on the other spaces and get some affinity. You don’t need to always do this, but its important to not let the MR linger too long.
In general, Warframe is a game that’s best enjoyed at your own pace. There are very few timed events, and even fewer that are rare (Plague Star and the seasonal ones come to mind), so you rarely feel like you’re missing out on something.