Best way to market internationally

Apologies if this is put in the wrong forum but I wasnt sure what topic would cover it properly.

I have just released a site in the UK selling digital downloads. We are well known in the UK and this is where our marketing takes place.

My search engine rankings are fairly good and we are pulling in alot of international traffic.

We are looking to market the site internationally, we are considering international affiliate marketing with industry specific foreign based websites.

What I wanted to know is, is affiliate marketing the best method to achieve international sales and apart from this and a high level of SEO what other methods could be implemented to achieve this?

Thanks in advance