I am a young computer science student from Europe(20 y/o). I'm scanning job market to see potential future positions that I might want to apply for. Right now I'm working as a trainee for a large corporation. I will probably prolong the contract, so I'm not worried about losing my job; However, I am not sure if I want to work for this company for long period of time - I think that I'm young and I would like to explore different areas of CS, maybe go to another country and work there.
If I resign, I will be looking for a new job in some (distant) future. I would like, when the time comes, to try to get job in some of well-known companies(which I think would be hard to find job at). Now I wonder - let's be negative and say that I fail, and they reject me - could this decrease my chances of being hired later in future, when I get more experience? Given the situation, should I try to apply, or spend some time polishing my skills?