I am saddened that I have to add this in because I have only recently heard of this one. Make sure the company you are applying to has a physical address, a website, social media. This is 2021, if a company does not have the latter two it should worry you.
Never pay for work. This is similar to Multilevel Marketing (MLM), where you have these upfront costs, however, these tend to not be MLM’s. They still want you to pay to work for them. This reminds me of the reverse financed internship ad that has been going around.
Use reliable job search engines. Check their Glassdoor and LinkedIn pages. In addition, depending on the country you move to make sure you join a union, generally, they have lawyers who will take a look at any contract to ensure that it is okay. This is the case in Sweden, but it might not be available everywhere.