I have applied for one previously.

You need:
* An approval from your sponsor.
* To have a good bank account record with a considerably good salary to show you can afford a maid.
* To be married (singles not allowed to bring maids).
* Marriage certificate with wife's residency in Qatar.

You have to decide what nationality you will apply for as you shall be given a visa for that nationality only.

The visa fee is 1,800 QAR for non-Qatari's

Then you have to find a local agent for employment of maids (plenty around), you look up a photo catalogue and pick your choice.

The agency will take between 7,000 QAR up to 9,000 QAR depending on the agency and the nationality of the maid.
This includes bringing her to Doha.
You pick her up from the agency and you have three months as a trial period before you have to do the residency and medical procedures for the maid. This will cost an additional 500 QAR.

Maids from Indonesia and Nigeria have the minimum cost.

The monthly salary range is 200 US$ (700-750 QAR).
You sign a two year contract and need to pay her return ticket after the two year period.

A friendly advise:
Bring a maid who has kids and has to pay for them, because she will be dedicated to her work for her kids. single maids usually have tricky moves and will cause plenty of problems to make you send them back...

Also, try to bring a maid that has no previous experience in gulf countries. These need a lot of teaching but serve you better than those with previous negative experience who are very lousy...

I have dealt with Al-Jasem near passport building at Medinat Khalifa.
Try to bring an Indonesian maid if you can...