Dan Martell founder of Clarity.fm has tips for you in this video https://www.youtube.com/watch?v=_Mm_q0X-R1c

Developing from scratch could be really expensive. I recommend building something with WordPress and validate as fast as possible.

You can take a WordPress directory theme or plugin and get it customized to fit your needs.

Start by watching this video https://youtu.be/bpONIUobOEQ

Before you ask money you will need to build something quick and dirty (MVP) and try to get few users to see if your idea can fly. Truth to be told that it’s going to be near to impossible to get funding unless your idea is

A. High-Impact for global change where nonprofits like Chan Zuckerberg Initiative or Gates Foundation can fund it.

B. The data you collect is so valuable that you can sell the data to make money.

C. You can get ridiculous amount of traffic to generate ads revenue.

In all the cases you still will need to build something while keeping things bootstrapped. I highly recommend you to build a desktop/web directory app vs native app to test your idea.

Use open source technology like WordPress. Google “best wordpress directory theme” and you will find something suitable for your need.

Here are some helpful reads
https://brainhub.eu/blog/build-app-non-technical-person
https://listingprowp.com/tips/why-99-percent-of-startup-ideas-fail

There several reasons but more often it's because you built a solution for a problem that didn't existed. You should focus on building something quick and dirty and get feedback from your real users. Try to have them pay for it. Here's a detailed article I recently published. https://listingprowp.com/tips/why-99-percent-of-startup-ideas-fail/

If you want to start building your own Yelp like directory for a particular city and industry but you are on a tight budget with limited tech skills I would definitely suggest WordPress.

But it can be tricky as WordPress has several different options and you can get easily lost and even it could end up getting very expensing if you don’t play it right.

Here are few helpful resources for you to go over and decide.
Adam from WPCrafter has done a very good job comparing top 3 WordPress products to build a site like Yelp, watch the full video here https://youtu.be/Ykid7UTXxYI

Then you can watch a step by step full video on how to build the directory here https://youtu.be/sRbUsQXyEOc

There was a detailed article by Codeinwp on the same topic that can be found here https://www.codeinwp.com/blog/create-a-local-search-directory-like-yelp-on-wordpress

Hope this helps you get kick started with a tight budget.

Google or YouTube "design thinking" and learn the process. It will definitely help you with early stages of idea validation.

Responsive web design basically means a website designed to adjust different device screens example desktop, tablet, mobile or even a smart watch. When you building a website it's highly recommend to take this in account and always go for perfecting responsive site before creating a mobile app version if you have to.

Hope you were able to find the right product to build a directory. IM so we can setup a free 30 mins call and I can advice you on this.

Meanwhile checkout ListingPro, wp version is on its way http://themeforest.net/item/listingpro-multipurpose-directory-template/13800879

I am an author on Themeforest and we recently got our Video portal theme approved on TF. You can reach out to me directly and share the link to your product. I can definetly give you some valuable feedback.

Link: http://themeforest.net/item/videofy-video-portal-html-template/16390488?ref=themedrone

I will leave it to experts and would start off by suggesting to watch a video on Idea Validation by @DanMartell the CEO of Clarity.fm http://youtu.be/gKDhDrSLp4E

Also here are few videos by Lean Startup Guru Eric Ries
https://youtu.be/hwlRxZJuWTY
http://youtu.be/fEvKo90qBns

Hope this help. You can always IM me and we can do a free call and I might be able advice or help validate your idea.