What steps can/should I take to become successful engineer?

You don't say which branch of engineering you're in, but there are some general principles which apply to all of them. Two important factors for success in any field are a strong interest in, even passion for the work you do, and a natural ability to understand and solve the problems that are part of

How hard is it to join NASA with just a bachelor's degree in aerospace engineering?

However difficult it might be, if you want to work at NASA, go for it.This should have jobs at NASA that reqire no more than a bachelors degree in engineering...  Careers at NASA

How hard is it to join NASA with just a bachelor's degree in aerospace engineering?

It depends where you want to work at NASA. At the research centers, they are bachelors working but I would recommend you aim for a Masters or PhD. At NASA Johnson, a lot more people have bachelors (or came in with bachelors) and are able to work in the Engineering or Mission Control Directorates. Long