As someone who runs a small (bootstrapped) startup in Berlin I'd recommend you to avoid the smaller startups, as you will often be paid under par and might have bad experiences like the ones you described. I'd go for larger and well-funded ones. Also, if it's not a must to work at a startup you could have a look at all the digital labs / hubs etc. that established companies like BMW, Daimler, VW, BASF etc. are opening in Berlin. They offer somewhat of a startup experience but with big funding and the standing of a large corporate behind the scenes, so you might be able to get a better deal there. I worked for such a spinoff before founding a company again and I really enjoyed it, great pay, nice work-life balance and friendly and savvy colleagues. Just my 2c.