I've been freelance for the best part of the decade, yet whenever I receive a cold-call email from a freelancer looking for work (like the one suggested above),

I've been freelance for the best part of the decade, yet whenever I receive a cold-call email from a freelancer looking for work (like the one suggested above), I generally either politely decline or mark as spam (if the tone of the email sounds like I'm one of 200 who were sent the same message body), even if I really could do with someone to help spread my workload. One key thing, for me, is that giving someone work requires _my_ trust in _their_ abilities. Some people might choose to base trust on a track record of projects listed on a CV, others on viewing someone's source code in a public repo, others might value personal recommendations, others might only trust people who they actually know from a not-too-distant circle of their professional network. I'm mostly in that last two camps. A cold-call email from a stranger: you'd be lucky to get a 2% genuine real-paid-work conversion rate, in my mind. A warm-call (I know that sucks as a term) email from someone I know via work or a conference or some kind of tech situation: far more likely to lead to work. So, network. (And it's not the same as nepotism.)