Net+ is a good cert to have. It will give you a good knowledge of networking basics which you will build on and refer back to when going on to get other certs. It’s a great place to start and will help you with many other exams, just don’t stop there! Transcenders are good for studying and there some that I am sure others can recommend.
Go to Amazon and look for some of the test prep books. They usually come in packages with at least a demo practice exam suite. I would recommend going through the practice exams until you can get at least 80% or better on a consistent basis. You should then be ready for the real exam. I went through the CNE, Security+ & C|EH certifications by doing this.