A good place to start would be pitching your friends and family. First, make sure you have a great story and are able to convey what you are building/problem you are solving to anyone. Some investors might not be familiar with your field, thus your first objective should be to convey your product to anyone (a 10 year old should be able to understand what you are doing).
Once you have a great story you can move on to pitching to other founders/investors, there are plenty of experts here on Clarity that can provide you with amazing feedback. Make a list of 5-10 people here on clarity who have experience pitching to investors, set up a call with them and get their feedback.