As a transactional lawyer who's honed my skills in Australia and worked across Australia and Asia, I've been involved in a variety of cross-border dealings and transactions. I've discovered that the most effective way to adapt to new jurisdictions and handle such matters is to maintain an open mind and a sense of curiosity. As an emerging professional, I would also urge you to consider working in different countries and jurisdictions. This could provide you with invaluable work experiences, particularly if your goal is to become an international lawyer.
International law is very vast. It can include areas such as human rights, environment, wildlife, cross-border trade, arbitration, among several others. (You may refer to the book "International Law" by Malcolm N. Shaw) It may be helpful to narrow down your interest areas within the domain of international law. You can then accordingly research the various internship opportunities, either in your state/country or abroad, with international law firms, international organizations, non-profits, multi-nationals, etc. It may be helpful to stay abreast with news in your chosen domain to be able to identify the major players who you might want to intern with or be associated with in the future.
All the best,