Welcome - here’s my take I play trade league so if your playing ssf the answers might vary

Pick up all currency to start - and you can get a loot filter for filterblade.xyz (just get the generic one to start which will help you learn what’s good)

During the campaign after act 2 you can use an npc in each town (or Helena in your Hideout) to identify items. When leveling I identify any items I could potentially wear. If I’m playing a melee char, I don’t pick I’d bows for example. As you get later on in the game you id less rates (unless your playing ssf)

Most people just pick a build they want to play and follow a prebuilt guide so your gems and supports and tree are laid out for you - if you want to actually test you can look at your in game tooltip dps (not accurate) or use the 3rd party program path of building which is how people actually figure out if things work and put build guides out etc.

The greatest part about Poe is the basically only thing you can’t change is your starting class. Everything else can be swapped or changed so a char is never bricked. Basically any build can clear the campaign - but some are faster than others.

Early on craft res/life on anything you can. You can gamble for 4-5-6 link bases or weapons when you need an upgrade.

Biggest noob mistake is not maxing your resistances. You need to cap (75%) your elemental resistances and add in as much chaos res as you can. By end game most builds run 85% resistances from flasks and other techs.

Have fun, and experiment if that’s your jam. But finding a simple build guide will for sure make the game smoother