The star chart doesn't open on its own — a short chain of story quests opens it for you, and the weakness you feel afterward is a mod problem, not a level problem.
The star chart doesn't open by itself once Vor's Prize ends — a short chain of story quests opens it, node by node, and most of the confusion right after the tutorial is just not knowing which quest to chase next. Once you're through that chain, the thing that actually holds you back stops being your level and starts being your mods.
Vor's Prize hands you a Warframe, a ship, and almost no explanation. The next quest that matters is Once Awake, followed by The Archwing — it teaches aerial combat and is a prerequisite for reaching planets that sit behind Archwing travel. Past that point, the star chart stops advancing through quests and starts advancing through Junctions: beat the Specter guarding a Junction node and the next planet unlocks, no separate quest attached. Work through them in order rather than jumping ahead — later Junctions expect gear you'll only have if you cleared the earlier ones.
Two quests further down that path matter more than everything else combined: Natah, which is the point the ambient lore actually turns into a plot, and its direct follow-up The Second Dream — the quest that unlocks your Operator and changes what combat looks like for the rest of the game. The War Within comes right after and unlocks Focus, the skill tree tied to that same Operator. None of these three are optional in practice: skipping them just means postponing content the game is built around.
Mastery Rank is the account-wide number that decides what you're even allowed to use — some weapons and Warframes carry a minimum rank requirement, trading with other players needs Mastery Rank 2, and pledging to a Syndicate needs Mastery Rank 3. You raise it by ranking up gear to its cap (leveling a weapon or Warframe all the way, not just owning it) and by clearing Junctions, among other sources. Reaching a new rank isn't automatic past a certain point — you have to pass a timed skill test first, and there's a cooldown before you can attempt the next one if you fail or want to wait.
The practical upshot: don't hoard weapons unranked in your inventory. A gun you never level is mastery you never collect, and it's also a gun that stays weak — which is the next problem.
Nothing in Warframe scales the way an RPG level does. A Warframe or weapon's real strength comes from the mods slotted into it, and unranked gear starts with barely any capacity to hold them. Matching a mod's polarity to a slot halves what it costs to equip; installing an Orokin Catalyst or Orokin Reactor doubles a weapon's or Warframe's total capacity outright, which is why veteran loadouts can run mods a fresh one simply can't afford yet.
Mods themselves get stronger through Fusion, spending Endo and credits to rank them up — and the Endo cost roughly doubles with each rank, so the early ranks are cheap and the last one isn't. If a build feels weak, it's almost never the character under-leveled; it's a handful of core mods sitting unranked, or capacity that hasn't been unlocked with a Catalyst or Reactor yet. This is also why a frame can look tanky on paper and still die instantly — health and shields are mod-dependent stats, not fixed ones, and a build leaning on shields specifically benefits from understanding shield gating, the short invulnerability window shields grant when they hit zero.
Break crates and containers for Ayatan Stars — don't sell them for credits, since they're worth far more traded to Maroo Kavassa for Endo, the resource that ranks up your mods. Farming nodes like Helene on Saturn are worth repeating specifically because they hand out resources — Plastids and Orokin Cells among them — that later weapon and Warframe blueprints ask for in bulk; running out mid-build is a common, avoidable stall. And don't spend starting Platinum on cosmetics before buying Warframe and weapon slots — slots are the one thing Platinum buys that directly removes a bottleneck, since a full inventory forces you to sell gear you might still need for mastery.
Steel Path — the game's harder-difficulty remix of the entire star chart, with tougher enemies and better drops — isn't something to chase on day one. It opens once you've cleared the star chart's nodes and worked far enough into the main story that Teshin, found at any Relay, offers it to you directly. Treat it as the actual finish line of everything above, not a shortcut around it.