The source I used was the section in my brain that teaches you how to survive to buy food haha
Okay, I´ll explain the steps I took when I first came, but remember, this was 1992 so things were a little bit different back then (but some things are the same).
I came to Austria when I was 21, no German, because I met an au-pair back in the states when I was 20. When her visa in the USA ended I came back with her. When we came to Austria she started going to the uníversity fulltime and did not have time to work, but we did get (which you don´t have the advantage) some schillings every month from her grandmother and her parents, which covered the rent for our small apartment. We still needed to buy food, pay to go out with friends, and buy transportation tickets.
The first thing I did was apply to an ad in the paper that was looking for people to distribute flyers on apartment doors and house doors, as people told me that it was common nowledge that illegals did this 8I had a visa but no work permit so....). It was true. The pay was crap (I think I got 10 cents per flyer) and after 2 weeks I stopped because 1) I was the only person not from an under-developed country doing this and I felt extremely unwelcome by the others - I think part of it was they did not understand why an American was there with them and I think another part was if I left one of their friends would get my job. And 2) Sometimes the person who brought everyone out would drop you off in an isolated town and you were really stuck there until they came to pick you up at 5 or 6 pm, even if you finished your work at 1 pm, you just sat and waited as you did not have enough money to go shopping or so anything (or I would not have been doing that job). It did pay enough for food, but just wasn´t worth it.
Then I hung some flyers at the university offering English lessons. This was pretty easy back then as there were not so many English native speakers here. I did this for 1 year (I gave lessons to about 2 students each month for a total of maybe 10 hours. Every month I always had 2-3 new students and the old ones stopped because of money or they were traveling overseas.
From then I get very lucky and can pretty much assure you you won´t get this lucky. I saw an ad in the paper of someone with a 3 and 5 year old looking for an english native speaker. They wanted to me to watch and speak english and play with their children 8 hours per day, 5 days per week, and the husband of the family was from a famous austrian folk band, so it was cool to talk with the band members and him and hear about their life. I also knew something was up when the lady picked me up at my apartment in a new sports mercedes and drove me about 45 minutes ouside of my city to a huge house in the countryside. I did stop after 6 months because I just got tired if it, and I saved money so I could stop.
I then placed an ad in the free newspaper and had occasional english conversation jobs, I taught one man who was 40 years old for 2 years, 2x per week ie 4 hours per week, and he paid me decent, so I only did it with him. After 6 months his wife, who worked a government job, said she had some work in her office I could also do for her (this was when I finally found out not only restaurants and crappy jobs have illegals working there, but even respected companies hire illegals - I even knew a russian girl who worked at schonbrünn in 2005 illegally - I think all government or city owned businesses do this, it´s just the average austrian or person does not believe it or realize it). So I worked there for one year. Then we got married and I just got a normal job.
In reality, nothing is legal, I don´t even think that private english lessons for pay is legal, but nobody will bother you about teaching English and getting paid for it.
I really think finding students to pay you for English conversations will be almost impossible in 2014. Place an ad in the free newspapers so that an older family man or lady will want private lessons or to babysit their children in English.
I know several people from Ukraine, Romania etc who do work as waitresses and waiters in small cafes, but it is all illegal. (After I got married I worked in the 1st district and it seemed like 50% of the workers in the city did not have working permits). I only saw one time where the people who bust illegals on the job (not sure what they are called) made the waitresses all leave and go home because none had working permits - but I only experienced that 3 times in 20 years so it won´t normally happen).
Almost every company I have worked at in Vienna has had at least 1 or 2 people with no working permits working there. It´s more common than people realize. The only way to find these jobs is to ask in the shop if they are hiring and tell them you are a student but have no working permit, and they will be nice and say either sorry no or they will say come back and talk to our boss at 5 pm. But I would only try smaller food places (cafes, restaurants, etc). I do know several Japanese restaurants in vienna have people without permits working, I assume the chinese, japanese, etc foreign cafes and restaurants do this more than the austrian owned ones do.
Sorry my post is so long, I guess the short answer is place an ad in the free papers for english conversation and babysitting, but don`t expect anything as it is much harder today than 20 years ago. I wouldn´t do anything else if I had a student visa though, but if you must, meet as many foreigners in vienna while you are here and you will easily find something.
I would personally help you, but I am self-employed so I have no boss to ask for you.
there will always be people who prefer to troll rather than help. 
, but I am sure it may be of great help to those who really want to get by and make a living. 
Working in Vienna
The work culture in Vienna
Vienna's labour market
Working in Austria
The labor market in Austria
Setting up a business in Austria
Internships in Austria
Accommodation in Vienna
