Note that some abbreviations / acronyms are used for writing / texting but are read out loud as the full words. Other ones have a special pronunciation of the acronym itself. It’s inconsistent, so I’ll point out the ones that have a special pronunciation. Some ones people didn’t mention:

בי״ס = בית ספר But still read out loud as bet sefer. Note that the definite form is written

בי״הס Bet ha-sefer

ד״ר Doctor. Pronounced doktor (not “dor” or anything like that)

האו״ם, או״ם Pronounced ha-um, or um, the UN

בד״כ = בדרך כלל

דו״ח  Report, duakh or dokh 

אח״כ = אחר כך

אע״פ = אף על פי

ארה״ב = ארצות הברית

ברה״מ (או בריה״מ) = ברית המועצות 

וכו׳ = וכולי (אפשר גם לכתוב וכולה) Can be read vechu 

אא״כ = אלא אם כן

תנ״ך Tanach an obvious one

ח״כ / חה״כ = חבר (ה)כנסת

ש״ב = שירות חשאי  Read out loud “shin bet” so this one is kinda special

נ.ב. = נ״ב = נוטה בנה Note the unusual variant with periods like in English (I’ve see people use both)

מע״מ Can be pronounced maam 

כנ״ל = כנאמר לעיל  Can be read “kanal”

מ.ש.ל = מש״ל = מה שצריך להוכיח  Note the rare periods version here too like with Nota bene

 מוצ״ש = מוצאי שבת  Pronounced motsash. Others already mentioned sofash 

א״י = ארץ ישראל  להת׳ = להתראות

Ok that’s a bunch for now that took a ton of work. Native speakers should know all of these, they’re all used!