In your novel, should you describe the signs your characters are making? Should you use a dialogue tag like signed instead? Can people who speak ASL (American Sign Language) also understand BSL (British) or Auslan (Australian)? What are name signs?
In my experience, signed is usually the way to go. Describing simple signs or name signs is usually OK.
ASL and BSL are only about 40% cognate, which means that a lot of information could be lost or misinterpreted. Dunno about Auslan. But the idea that people with the same spoken language share a common sign language should be rejected. There are many other forms of sign language just within English-speaking areas. SEE (Signed Exact English) is one. Every interpreter I know hates SEE.
French Sign Language (LSF), on the other hand, can be more than 60% cognate with ASL.
Name signs are signs that denote a particular person. You do not get to choose your own--a Deaf person has to supply you with one. They need to be fairly simple so that they can be used in quick conversation, and they need to be meaningful enough that they really describe something memorable about the person being referenced.
When talking about other people, the Deaf community may be what hearing people would consider insultingly blunt--Fat Gay Tom and Cross-eyed Black Tom, for instance--but that's necessary for clarity. Fat Gay Tom and Cross-eyed Black Tom won't take any offense, though any eavesdropping hearing people might.
For full disclosure, I don't speak any sign language. My Beloved, however, has been a professional ASL interpreter since forever. While I've learned a lot from her, I still have to pick her brain for the answers to these questions.
Anything else about ASL, sign languages in general, or the Deaf community you'd like to know?
In addition to signed (or just plain old said), voiced is another tag you can use. It indicates that someone who signs is vocally speaking.
The interpreter signed to John to hold on a sec, then she voiced to me, "Stop interrupting!"
Someone wanted to know what the hardest part of being an interpreter is.
My local interpreter responded, "Prison sex phone calls."
She was only half joking. It happens, and some terps won't do them. Then, there's this guy (https://nypost.com/2015/09/26/guy-calls-deaf-service-4000-times-to-masturbate/).
Most other problems are caused by Stupid Hearing People™ who are taken aback and don't quite know how to proceed when confronted by an interpreter. They'll talk to the interpreter, tell the terp to ask the client a question (client's standing right there!), and sometimes refuse to interact at all.
Other problems are caused by Deaf people who sign sloppily or don't pay attention to the terp. For phone calls, the Deaf person's phone might be pointed at the ceiling or randomly whip around the room like an amusement park ride as the caller talks animatedly.
Yet other problems are because of the system, especially for phone calls. Do not announce is a directive Deaf people can give the interpreter, which means that the terp cannot tell the person on the other end of the phone that this is a Deaf person using an interpreter. If the Deaf caller is male and the interpreter is female, the first thing the hearing person might hear is a female voice saying, "Hello, this is John."
And yes, ASL interpreters sometimes get asked how long it took them to learn Braille.
Personally, I'd use descriptions of signs sparingly. John asked, Betty said, Chris signed are usually sufficient.
You can gloss the occasional idiom (though you might leave off the all caps).
FISH SWALLOW (means "gullible.")
FORK IN THROAT (means "stuck.")
TRAIN GONE, SORRY (means "too late, we're done, it's over." Things like that.)
Halloween isn't a thing in all countries, but for those who celebrate, here's how to sign Happy Halloween! from 90 different countries (Facebook link):
https://www.facebook.com/exploretheworld2017/videos/1656876901029664/
How do you deal with jargon in ASL?
Same way any language does--they have signs for it. Of course, not everyone fluent in ASL will know all the signs for everything, just like most people fluent in English will not know all the words in a treatise on brain surgery.
So someone could have extensive knowledge of (for instance) prehistoric megafauna signs, but know very little of astrophysics signs.
When all else fails, it comes down to fingerspelling.