Coincidentally, at this stage in Part IV of Disciple I need to introduce a bevy of new characters. Six, in fact. All of whom have titles. For extra complications, there are also going to be a handful of background characters that the reader doesn't need to pay attention to.
This is easier to do with pictures, admittedly, but a strong visual element attached to a character is an easy way for the reader/viewer to tell them apart. We do this in real life, too -- which is why when somebody gets a drastic haircut, for example, we might not recognize them for a moment. Or if someone you always see in a business suit turns up in jeans and a t-shirt.
I picked a distinctive feature to emphasize when the character was introduced, and I'll sneak it in quickly the next time they turn up. I can't do this with all of them, though, or the cues themselves would become an avalanche.
In my case, I put one of the new characters in a distinctive blue uniform. Nobody else of importance is wearing a blue uniform, and now that it's linked to her, she'll be wearing it throughout the story. But that's reasonable -- it's her uniform, after all, and she's on the job.
In prose, unlike TV/movies, we can also invoke smell or texture cues. If it's reasonable.
Unique speech patterns
A lot of people hate written brogues -- I suspect most of that stems from when you start replacing syllables with apostrophes and words become unrecognizable. But they can be an easy way to differentiate characters, so long as you don't hit the reader with six different brogues at once. Or more than two, really.
I did not have this aspect to play with, unfortunately, because of who these characters are. But it could be useful in other situations.
Strong, distinct first impressions
How fast can you sketch a character? The personality, not the appearance. A clear personality will separate any character from the crowd -- important when you've got background characters that aren't important at the moment.
In my case, one of the characters was introduced, described (I assume the reader will promptly forget that) and then opened her mouth. Hopefully, what came out stamped her with a big, red CLUELESS.
Another one got in an MC's face for an alpha-dog staring contest. TROUBLE.
The point is for the characters to hit the ground doing what they do best. What they'll be doing most often. We don't meet them on an off day or in an oddly introspective moment, because it's that first impression that sticks. This is just as important for the supporting cast as for main characters.
Spread it out AMAP
Breaking up a slew of introductions with some familiar faces to remark on the newbies, give the reader a little breathing room, helps too. The more you can break it up, the less it will feel like an avalanche of information, too.
Since I had six to throw at the readers, I started by introducing just two. End of scene, little bridge scene, then the big introduction scene for three new characters. End of scene, a few of other scenes, plot developments, and number six will be joining us a little later. Hopefully this will minimize confusion.
... and then I'll give it to my betas and see if it worked.