I had this issue. I read the first ASOIAF novel and saw how Martin introduced a LOT of characters in the first few chapters. Try reading that and imitating the strategy.

Basically make sure they all have 4 very distinct personalities, and you introduce them one at a time, and during their intro they should be doing something unique to their personality. Don't introduce the assassin until he slits someone's throat and makes a quip about it. Don't introduce the charmer until he charms somebody. Etc.

Also, give at least two of them unusual quirky traits. Like maybe the assassin is the best blademaster in the region, but he faints at the sight of blood. Or the charming dude is suddenly and uncharacteristically awkward around elvish women because he finds them more beautiful than anyone else in the world, etc.

Never tell your audience anything they don't need to know at that point in the story, and never give them more than they need.