You will need to re-run the presentation a few times by yourself and a few times with different audience before you take it to potential investors, reason being that you must close off any opportunity for someone to ask a question. How do you do this? By thinking and re-thinking every point and looking closely at your research, sources and making sure you have covered everything. You know you have succeeded when very few questions are raised after you do your presentation.
Think of having a new investor as dating, you should not let out too much on the first date, yet you should be open and honest with whatever you let out. Again just like a new relationship you should be know more about each other every step of the way and be willing to grow together.