Going to college in a different country?

Step 1 - be sure that what college means in your country is the same in that country.

For example, in the UK college is for 16-18 year olds (similar to high school), whereas it's obviously different in the US.

Assuming you mean university in most countries; you'll need to get a student visa. This requires a confirmed full time university place (entry requirements depend on the university and course), and proof you can afford the full cost of living and studying there.

Are you going to graduate school in the US? Or do you want to have a professional job that requires a license? If so, with the licensing organization or grad school take a degree from wherever you are going? You probably cannot get US backed student loans for out of country studies... and if you are not a student or resident... you may not qualify for loans in the other country. This would requited A LOT of research, cost estimates and preparation.

It's not harder but it's more expensive and there may be more red tape if you need student loans.