That basically leaves one option: call centers. For non-specialists, call-center work is not pleasant or well paid.
That just about sums it up, along with a bit of teaching if you're lucky. Although some teachers have currently upped their fees, it's because they are trying to make up lost ground for the work that's dried up. Those who are earning regularly are taking 40-50zł per hour in these parts, from what I can gather. Odd exceptions doing better perhaps, but generally it's not a good living. (Good to see you post again, Dom, btw.)
As for other jobs, here I speak with personal experience for sure, from past efforts. You need an in demand specialism, it's usually IT and it's usually not as well paid here as it'd be somewhere else. If it's just working as a native of English, teaching is all there is (see above) with very occasional alternatives quite possibly filled by the company manager's friend after a pretend recruitment process (for paperwork and officialdom reasons) wasting external candidates' time and effort. Native Eng speakers who have good jobs here usually get them from a friend or are posted by their home country to Poland. If that blessed scenario is bestowed upon you, you're going to love it, because you'll get UK or US money here or near enough.
In the real world though, it's have a good self employment idea and try to get enough money in to cover the mandatory ZUS, or teach to just about scrape by if you're lucky.