I’d get a bunch of cosmetics and save a bunch for Warframe and weapon slots.

Being able to customize your gear makes it a lot more fun to use IMO. Since you can farm for functional items like Warframes, weapons, mods, etc., I find it nicer to just follow the progression of the game.

I recommend checking out Color Pack: Alpha, Color Pack: Beta, (maybe the Kuva Lich Hunter Collection), the Shi armor set, the Sigma Series armor set + syandana. You can also just have a look up armor sets and syandanas in the Market to see what’s available.

There’s a % chance that the G3 will appear in the first few minutes of any Grineer mission. So, just do a bunch of short-ish missions and they’ll appear eventually. IMO it’s not really worth actively trying to get them to show up.

Try Nyx. Being able to stip all of your Sister’s Shields and Armor makes them very squishy.

IMO you’re better off without guides. They usually steer you in a pretty specific direction and often focus quite a lot on ‘efficiency’, which might not be the most fun experience for you.

The most important thing is setting goals for yourself. It gives you a solid point to work towards, which helps with motivation, and allows you to determine which parts of the game you can ignore for now, which can help you feel less overwhelmed.

A good goal could be unlocking X planet, farming Y Warframe, completing Z quest, etc. As long as it’s interesting to you, it’s good.

As for learning how stuff works, you should be able to grasp most of the important stuff by just interacting with systems as they become relevant. If you’re not sure how something works, you can ask in the in-game Q&A Chat.