As a first time tech entrepreneur, I was confused if I should select one tool for mobile prototyping and other tools for implementation. I wanted to deliver my mobile app service as soon possible but I don't want to make mistakes when selecting tools. I have seen tools like Appcelerator, https://codiqa.com/ and PhoneGapp. Other than that should I also develop for android and iPhone separately, or should I use one of the above tools to develop once and deploy in different devices? Time and money is also a constraint for my startup. Please advice me. Thanks.
It depends on which stage of prototyping you are ..
If you are still in sketching and ideation, Balsamiq is simple and to the point.
Once you have the idea designed, I recommend you hire a graphic designer, do the high fidelity images and buttons for you on photoshop , as , any way, you will need them for your developers too.
Whether you are at the balsamiq stage or the high fidelity images, I recommend you to go to invisionapp.com . I use it to show / demo simulate a full workflow from the images I have.
It will also help you discover gaps in your workflows that you didn't design, or what to improve in the workflow before you start working on implementation.