What is the most effective to reach your desired job in gulf area by Web sites applications , employment agency or what?

In my point of view you should do both of them & i do agree with the answe given by Mr.: Mohammed saei too

The answer is found in the concepts of public relations, if we can make sound public relations with others, then what we need will be attracted to us.

I Think you have ot try both of them .

There are two things here 

1. How to reach the employers/recruiters ?  this could happen by many ways and using different means and methods including employment such as BAYT
2. How to click with these employers/recruiters ... and this has to do with your credentials and how fit you are for their expectations and requirements 

In my view, you either need direct personal connection with the employers, or you may come under well-known and reputable companies as their employee, or you should have outstanding credenetials that speak for themselves 

The both way are accepted. 

but I think Employment egency is a higher chance. 

And also I agree with Mohammed Saei. 

The best is direct physical application by committee interviews in the country of employment request.

Then websites and last is the agencies.

I echo with the answers of Rafaat Sallam and Mohammad Saei

the best way is too keep an eye open, but chances are more in

1. Through Contacts/Referrals/Social Networks

2. Employment Agency

3. Local newspaper

try evry possible way