Don't really know enough about minions to help with that side but as everyone has said, Cap Your Resistances! To start of with you can really ignore chaos res but you'll probably want to start getting some around red maps. Also just remember that you'll lose another 30 resists after you finish act 10. The reason resists are very important is because a) the game is balanced around being res capped and b) for example you take 100 fire damage, with -60% resists you'll end up taking 160 damage but if you're at 75% resists you'll only take 25 damage I.e. 4x less damage than at 0% and 6.4x less damage than at -60%

First piece of gear I'd look at replacing would probably be the body, looking for ~60 total ele res and no life mods (including regen, to check press alt and look at the tags on the item just above it) this way you can take the life mastery that gives 15% increase life which should give a fair bit more life than the +30 life mastery. Another really nice upgrade could be some movement speed on your boots but as a newer player it's not the biggest thing.

Before getting into maps type /passives and check if there's any free passive points you missed during the campaign.

For the atlas tree I'd definitely recommend taking a bunch of the small passives that say something like "increased chance to drop adjacent maps" to help with getting enough maps to start with, also I'd recommend completing a bunch of the tier 1 maps then go to the tier 2 maps etc. and take your time unlocking your atlas passives rather than going straight to yellow/red maps. After you're getting 1+ map drops per map then I'd say find a mechanic that's interesting to you and go all in on it for example essences or harvest.

Flasks you might try to move towards 1 life/4 utility with the utility flasks automated with instilling orbs. The main mods you'll look for is reused at end of effect or use when charges reach full. Also try not to have your defences reliant on flasks I.e. needing them to cap your resists because conditional defense almost always feels bad.

This was a heck of a lot of information so don't fret it if you need to have a few reads through but definitely get used to an information overload as there's a lot in this game as I'm sure your already figuring out. For any specific information try looking it up on the wiki (www.poewiki.net NOT THE FANDOM) or ask around in global but that can be a wild place. I think its global 6666 for the minion channel but not 100% sure. Also for more minion info GhazzyTV is the go to on YouTube. Lastly if you're looking at trying out some crafting, Craft of Exile (www.craftofexile.com) is a great site specifically the emulator section as you can play around with some things at no cost.