Write It Fully, Don't Abbreviate

It is recommended = Mustahabb = for the person who writes
out Hadith, that he writes out = ﺻَﻠَّﻰ ﺍﻟﻠَّﻪُ ﻋَﻠَﻴْﻪِ ﻭَﺳَﻠَّﻢَ = Sall’Allahu
Alayhi wa Sallam = when there is the mentioning of the
Messenger of Allah. He must write it out fully, not merely
using abbreviations, {like S.A.W, PBUH, s.a.w.s} and neither
sufficing on one of the two, {meaning you have to say the
Salat & Salam}. {Sharh Sahih Muslim, Volume 1, pg. 39}

What is Preferred to say after writing the names of Allah
Ta’Ala or the Prophet ﺻَﻠَّﻰ ﺍﻟﻠَّﻪُ ﻋَﻠَﻴْﻪِ ﻭَﺳَﻠَّﻢَ or companions or
scholars

Allah ﻋﺰ ﻭ ﺟﻞ
It is preferred/recommended for a person who writes out a
Hadith, that at the time he comes across the mentioning of the Name of Allah to add after it:
A’zza wa Jal
Ta’ala
Subhanahu Wa Ta’ala
Tabarak Wa Ta’Ala
Jalla Dhikruh or
Tabarak Asmuh or other similar statements.

The Prophet Muhammad ﺻَﻠَّﻰ ﺍﻟﻠَّﻪُ ﻋَﻠَﻴْﻪِ ﻭَ ﺳَﻠَّﻢَ
It is also recommended to add after mentioning the name of the Prophet Muhammad the following: ﺻَﻠَّﻰ ﺍﻟﻠَّﻪُ ﻋَﻠَﻴْﻪِ ﻭَ ﺳَﻠَّﻢَ .
This should be written out as it is, without using any
abbreviation and using both the “Salah” and “Taslim” on the
Prophet ﺻَﻠَّﻰ ﺍﻟﻠَّﻪُ ﻋَﻠَﻴْﻪِ ﻭَ ﺳَﻠَّﻢَ not just the Salah or Taslim.
The Companions ﺭَﺿِﻲَ ﺍﻟﻠَّﻪُ ﻋَﻨْﻬُﻢ

If a Companion is mentioned then it should be used after him
ﺭَﺿِﻲَ ﺍﻟﻠَّﻪُ ﻋَﻨْﻪُ = Radi’ Allahu Anhu and if he was a companion that
his father is a companion as well then it should be written ﺭَﺿِﻲَ
ﺍﻟﻠَّﻪُ ﻋَﻨْﻬُﻤﺎ = Radi’ Allahu Anhuma.

The Scholars ﺭﺣﻤﻬﻢ ﺍﻟﻠﻪ
The same respect should be used in regard to the scholars by writing and asking Allah to be pleased with them and shower them with his Mercy.

All these additions should be written even if they were not
mentioned in the original text the writer quotes or writes from because this is not a narration but a Dua’ = supplication… They should not be bored from repeating doing so, because whoever does not pay attention to it will surely miss a great
reward and a great blessing.”
~ Muqaddimah Sharh Sahih Muslim, Imam an-Nawawi (Rahmatullahi Ta'ala Alayh)

ﺁﻟﻠّﻬُﻢَّ ﺻّﻞِ ﻭﺳَﻠّﻢْ ﻋَﻠﻲ ﺳَﻴّﺪﻧَﺂ ﻣُﺤَﻤﺪ ﷺ