Sit down with pen and paper and decide what you want the app to do, list down the features, you can use akina Adobe Experience designer or sketch to design the UI/UX or an idea of what it should look like and do.....powerpoint achia 18th centrury..... Adobe XD ni free.............
create a prototype of the app, you can use free or trial hosting platforms for this........a prototype will help you create a budget......
tumia prototyoe to approach your investors, prototypes huwa way better than ideas on a Powerpoint presentation....
create the betas and invite users to test it out, iron out the bugs and implement new features .....
when stable tolea watu version 1
..........................
my opinion, corrections are welcomed