One important thing is to find out during the interview whether the company has a plan and they are not just hiring you to perform monotonous, undemanding tasks

One important thing is to find out during the interview whether the company has a plan and they are not just hiring you to perform monotonous, undemanding tasks. They should be able to tell you what upcoming projects you are most likely to work on in the near future. Also thoroughly research the company and its business domain, and make sure it is a fit before accepting an offer. Fog Creek scores a 12 on the Joel test, and it is not a bad place to work, but a lot of people would be bored out of their skull working there. Management is also very, very important. There is not much use having rock stars as colleagues if the people at the top making the decisions are not competent. That's a situation I found myself in at my last job, and it was very demoralizing.