Our social media is awash with mean wells and amateurs giving out sign lessons, most of which progress no further than the ABC of a few numbers who are sadly encouraged by deaf to 'carry on the good work' ATR says make it stop basically, too many are being encouraged to skip vital aspects hearing needed for sign to work for them, or aware it won't for non-signing deaf.
They can help by mostly dropping the culture gig/lecture/advice, and sticking to the effectiveness of the sign they are learning. Deaf critics wading in with 'please don't use English' etc are a pain and a hindrance, but everywhere, also BSL awareness ISN'T awareness of deaf people and BSL isn't awareness of hearing loss.
Using aspects of Signed English is acceptable, we don't have issues following. Far better that than regional sign and assumptions all deaf follow that too. It (!) is important as little is left out as possible, you cannot assume every deaf signer can fill in the gaps, we don't, despite some claims, are able to mind-read every one. Deaf are a literal set up they don't fill in gaps often and can misunderstand.
You cannot pitch too 'low' either, (It's called 'dumbing down' in some areas), not all can follow with 50% of detail left out. You have to be careful aiming over their head too. A lot of deaf struggle because they lack English as English is the primary means hearing use, we don't want to deter learners by being culture-specific, because sign is a communication assist and doesn't need a culture or history to work. Hearing or deaf can master it.
I also think it vital ALL learners try to speak as well, because sign needs lip-reading, and facial expression etc, that is how we fill in gaps. No deaf are sign dependent only.
There is a HUGE difference between ABC sign and sign used in Education and learning etc, so it is important learners don't assume the ABC assists the deaf in those contexts because you won't know how adept or qualified deaf are that way, and it can cause offence if you ask.
All BSL Interpreters are well aware of this, and have to adjust their level of signing according to the person they are signing for. Albeit I think a lot just don't have the time to assess a client so adjust as they go, not ideal! With 40% of deaf assumed to have learning difficulties as well no one 'sign' fits all.
Learning the alphabet and counting to 10 won't qualify you for anything.