Focusing on a particular niche such as type of player, games, offers would definitely help. Having the country specific domains does play a role to impact the prospective site visitor.
As mentioned by Martyn, special offers and promotions via newsletter in the respective languages to the registered db of prospective players might help in improving conversions.
And most importantly getting to know the smaller details of the markets that you focus on would be the key. Some countries are very particular when it comes to using online payment methods. Using this to promote the popular payment modes for player deposits of a particular market/region should give the numbers a boost.
Having the correct landing page would be one of the final obstacle to clear for that very anticipated conversion. Colors and themes used on the landing pages for a market that is being targeted does impact the required goal in a way.
Hope this helps.