While a great idea is important, great execution is far more important.
You need to be able to communicate your long term vision clearly to your investors, and present it in a way that includes their long term incentives as well (how will they get returns?)
There are many places you can find investors:
Friends, Family, and "Fools" (basically people close to you who will support you)
Angel syndicates / angel communities (they are both online and offline)
Online platforms like Angel.co, LinkedIn, BEAMSTART
Crowdfunding platforms
List your startup in online directories focused on fundraising
Referrals of clients/friends/other investors
The key is to get a few smaller investors in who can support you in finding more investors.
An idea for an app or startup might not worth anything until the idea is executed well and converts into traction (users and/or revenue).
You might not want to pitch to VC if it’s still in idea stage, reason being, they will not be interested, unless you are a serial entrepreneur who exited a startup before. Approaching angel investors might be a better idea. Friends & family or experienced partner who has experience in your industry.