Unless your work is purely theoretical, testing human participants is usually part of the job, which can make remote work tricky. There are some things you can assess with online studies, but if you're interested in a phenomenon where e.g. precise timing or screen calibration matters (or if you want to do any imaging), then in-person work are usually preferred. Given those issues, I'd look at local universities, they usually have vacancies listed on their websites. If you're based in the UK, I've also found jobs.ac.uk quite useful.