The easiest and cheapest option it to take a local train ("Schnellbahn"), which goes directly from "Flughafen Wien" to "Praterstern". I do not recommend to take the "City Airport Train / CAT", because it is more expensive and you have to change trains in "Wien Mitte".
Take a "S7" or "REX7" from "Flughafen Wien" to "Wien Praterstern". A single ticket is 5.20E and the journey takes 27 minutes. This train runs between 4:30 and ~1:00, so unless you have a very late / early flight it's the best option. There are two to three trains an hour.
You can get the ticket at tickets machines in the airport itself (where there are often queues) or before taking the last escalator down to the platform (less crowded usually)
That's the green branded "fast train" going between airport and "Wien Mitte". It takes 16 minutes, but you will have to change in "Wien Mitte" to take another local train or tram to get to Praterstern, so you will definitely lose the time benefit. It costs 14.90E for a single trip, and you will have to get another ticket to get to Praterstern, which costs another 3.2E.
https://www.cityairporttrain.com/en/
Makes even less sense than CAT
https://www.viennaairportbus.com/
Taxis of course are available. Here is one well-known taxi company offering a 42E service in one direction:
https://www.taxi40100.at/flughafen/zum-flughafen/
Take the exit "Lassallestrasse", which is the less frequented exit. If you arrive from the airport, continue in the same direction the train went. Go down the stairs (or take the lift), and exit to the right. You will see a rather big road ("Lassallestrasse") which you just have to follow in north-east direction. In the third block (on the left, i.e. the side your walking on) you will find the ibis hotels.
Here is a screenshot showing the way.