The decent thing about targetting Europe is that you have so much to go at and not only that but most countries have English as a 2nd or 3rd language so your sites are still read and understood by someone from France, Spain etc.. However, translating your sites will no doubt have a positive affect on conversions as long as the translation is true and not sent through a web translation tool.
Spend time on researching what types of games people from particular countries play, personally I would say that Europeans play more table games to slots. If you also find this is the case then try to include sections on your sites and forums tha include detailed information about the games, rules, payouts etc.
As always, offer up a newsletter to attract players to sign up with you, then mail them monthly with special offers as you would with your current lists. When doing so, if the mail is in English then keep the language simple and to the point. Slang terms mean different things in different places, for example. ‘I love fruit’ means something a whole lot different in the US than it does in the UK. :shakebutt
For translated pages check out the local search terms that you think you want to target and see the results on this to see if it is worth it. Look at competitor affiliate sites in Google and see what they are doing as this will give you an idea of what seems to work best in that area of the world.
The main thing to do is to work to your strengths and look to get help on the language front to help you progress and break in. Work on one stage at a time and build your sites gradually so not to swamp yourself.
May even look at registering new domain names such as .co.uk’s .es’s .fr etc