(I'm in North America, but have lived and worked in 3+ Western European countries).
Beyond basic technical qualifications, these additional steps have helped me onboard a good sized team of part-time and full-time freelancers around the globe:
* Include 1 very broad, and 1 very specific question in the job posting (don't make them required -- see who answers them of their own volition). You'll get a sense of reading comprehension, and the care someone will use in responding. The questions should not require an essay in response, but neither can they be fulfilled by a templated response.
* For higher level candidates, offer to get on a 5 minute video call and share a calendly/youcanbookme link. Ask for a problem synopsis and see how complete it is, and check how many unclear potentialities get called out in response.
* For lower level candidates, look for 5, hire and onboard 3. In a slack documentation channel, include an on-boarding document with 3-5 steps (update avatar, include available hours in spacetime, post a hello and basic introduction in #general, add themselves to #somechannel, etc). All my keepers very faithfully followed really basic requests. The people who most vociferously wasted my time could've been disqualified at this stage of the game.
For this last step, pay for their time and set a 1 or 2 hour max budget at the start. Don't train or lead anyone through this process. That's not a road you want to spend any time on, because it will become an expansive sinkhole.
I've found that there are plenty of talented professionals out there, but those who can be useful, engaged, remote resources are a special breed. You want conscientious forthrightness.
