There are very few companies in Doha who are doing professional advertising in Qatar. There are lots and lots of possibilities but you should have a very good PR for it. There are some companies who are advertising their Brands/Products through Print Media like, Mupis, Bill Boards, Window Displays, Security Gates etc on a regular basis. If you can get hold of few big companies you dont have to worry. You should be competitive in terms of price, quality and punctuality and there should be someone who can get you into those major companies who are advertising a lot. Wish you good luck.