Chance Of Getting A Research Internship In US/Canada For Non-US Residents? I completed my undergraduate study in computer science outside of the US. I hope to obtain a PhD degree in Human-Computer Interaction (HCI) in the US, but I don't feel that I am qualified enough (in terms of research experience). So I am hoping to find a research internship opportunity in US/Canada. 

I could probably find relavant projects in my own country, but I feel that trying US/Canada first is more straightforward. After all, it's in US/Canada where I am looking for a PhD degree.

I have a few HCI professors in mind, with whom I would like to work very much. Should I contact them for internship opportunities? What are my chances and more importantly, how can I improve my chances?

Some facts that I think are relavent to the question: 

I am not a US resident so I will need a VISA. I don't expect assistantships (it's up to the professor). I have already learnt the basics of HCI and I know the fundamental research methods (through reading and auditing classes). My undergraduate university is not the best, but it's surely one of the best universities in my country.
You should simply send an email to the supervisor you are interested in. Your best help to be accepted to any program is to have the support of a professor. In US/Canada you should just start by, Dear Mr/Mme, X. 

Now, to convince the professor that you are a good fit, you need to convince him that you are have research potential. This is what the university will be looking for too.

You could talk to him about your interests, and how they recoup his (assuming they do by OP post). If you have done any research in that field you could mention it.

If you can find and read first a relevant paper he wrote and have questions about it, ask. I you can't because they are too complicated (which may really happen), or behind a paywall to which you don't have access, you could ask for a few classic references to get started.