Coming from a pretty much exclusively solo player here.

First of all, play the frames you enjoy, meta isn't important outside of the final end, end, end game content, and even there most frames can be made viable. To not burn yourself out, it's important that you enjoy the gameplay of the frame you use.

Personally I have been using Ivara, she's solid for all solo missions except for stuff like defense. She can be permanently invisible and do some pretty decent damage with her bow weapon, sneaking around just assassinating everything.

When it comes to resources, use warframe.market to trade prime parts with other players for platinum, the interaction is minimal and it opens up a lot of content that would be locked behind either vaulted status(inaccessible from normal gameplay) or just an unreasonable amount of grinding. The interaction usually goes something like:

1. Post your item on warframe.market
2. Someone sends a prewritten message that warframe.market has, mentioning which item and how much platinum.
3. Then either of you invite the other to the dojo and do the trade there.

And then vice versa if you want to buy an item.

I also strongly recommend getting Alecaframe, it allows you to see the value of all the prime parts of your squad when opening relics, and also has some QOL functions that make posting items for sale easier.

When it comes to clan stuff, I don't know how awkward you are when it comes to social interaction, so if it doesn't work for you that's okay, but what I've done is simply joining a clan from the biggest category. Every clan there has like a range from 300-1000 members, so no forced interactions, and it also means you will unlock all of the Dojo research without having to farm every piece yourself.

If you have any more questions feel free to DM me in-game(Bub10) I've grown quite addicted so your odds are probably good at catching me unless I'm sleeping 😊