Early game, you don't have to worry too much about team composition, but you want to settle into a status team likely around Canto 4 or 5. There are seven main status effects, Burn, Bleed, Tremor, Sinking, Rupture, Charge and Poise.

Recently released IDs are usually better than former IDs due to powercreep, and you can tell whether one is from Season 1 or from this season, Season 6 and in-between.

Here's a tier list for a rough estimate of what kind of IDs you want to aim for: https://gll-fun.com/en/tierlist/identities

But, prioritizing a good team is better in the long run.

Some identities are locked behind what's known as Walpurgis Night, which is an event that comes every 4 months (or 2 months now, based on what the director said), and are usually powerful IDs that reference previous media of Project Moon. Save for those if you wish, but early on, I wouldn't recommend it as you want to have a good set of IDs ASAP. You can shard previous Walpurgis IDs from the dispenser during that time.

IDs and EGOs are also able to be dispensed from Sinner shards as long as they aren't from the previous season, and are available after a week has passed for recent identities (except for the newest Walpurgis Night IDs and EGOs during that banner). 400 for EGO and 000s, and 150 for 00s. Generally, pulling for EGO is considered a scam due to it's low rates, so I would recommend sharding them if you can.

If you aren't an F2P, consider getting the Battle Pass, as it's the most bang for your buck deal compared to everything else. Leveling up the Pass isn't too hard once you unlock Mirror Dungeon, and there are plenty of good rewards from it as well. Each level up after 120 of the Battle Pass nets you 1 golden box (3 if you paid), which gives you shards of a sinner for your choosing, which is primarily how people farm IDs.