best advertising option for programming tutor

what is the best paid or free way to advertise a private tutor?

and i dont mean those directory sites they will not help at all, only the top tutors get sales.

the target audience are mainly computer science students or people who want to learn java etc.

for 30$ per hour to get to 1500$+ i need 60 hours , this means 60 students that take 1 lesson per month, 3 who take 20, 6 who take 10 etc etc.
to get a full time salary i need a bank of 200 clients (im giving a rough goal estimation).

how meany people do you think i need to reach? 5000 and 200 convert? 100k? one million? 200k?
shod i use google ppc? cpm? udimi solo ads? and how much shod i invest? out of 1500$ estimated profit?

thats hard business how dose tutor agencies do it? they have an investor and they gamble with his money on ads? they need 3 times what i described as they are a middlemen (or pay less and swindle their tutors and clients ).

any advice? dose this venture has any hope?

my only problem is internet marketing and effective marketing roi etc.

How is the tutoring being done (skype, in-person, etc), how many students do you currently have, and are there any large colleges nearby? For such a competitive niche, local marketing will be far easier, but it's still going to take a lot of time and effort to get $1500/mo post-tax profit.

tutoring done by teamviewer, i have 2 currently but they are repeat clients so this is good.
i want global marketing so i can work from anywhere.
i thoght about contacting university's around, that can be an option. but again im want students from the usa mostly (im not from the usa).