Navigator WAZE
If you rent a car, I recommend to download the free navigator WAZE
https://www.waze.com

After getting off the highway, look for a sign "Old Talpiot" Just follow it and you will get invariably onto Dev Hevron (see attached maps). Follow it until you get to Ein Gedi - take a left there. Up the hill, Ein Gedi becomes a one-way-street - take a left into Efrata and then take a right twice and you are on Beitar Street. After Ein Gedi, take a right after the second house.

The entrance is on Carlebach Sreet, more a walkway than a street. It is also the entrance to the parking lot which has free parking. Please be sure not to park right at the house - you would risk getting a ticket. The apartment is the last one on top of the stairs.

Sherut
If you are taking a sherut, a shared taxi, from the airport: just keep walking straight after getting out of customs until you are on the street. Sheruts are parked to your right. Your destinatination is Beitar 22 Old Talpiot/2^nd house after En Gedi. Fare is about 70 NIS, when I took it some time ago

To book a sherut return, call 6222553 from the apartment phone, one day before departure (not earlier, not later)

Using the Bus
To use a bus, you now need a chip card which can be purchased at many places. One place selling chip cards is in the shopping center on General Pierre Koenig St down the street En Gedi a little further down from Dev Hevron.