ITM: Initial Target Market
Learn to swim in the swimming pool first before diving into the ocean.
Getting a product off the ground and getting traction is hard. It's like trying to swim for the very first time. You don't want to learn in the ocean, you want to learn in a shallow swimming pool and with inflatables and only then, go have fun in the ocean.
Your inflatable is known as your MVP (Minimum Viable Product, but I personally prefer to use the term MAP for Minimum Awesome Product), whereas your swimming pool is your ITM (Initial Target Market). Don't try to target everybody from the get go. Identify a group of homogeneous people who share the same needs and who have the lower resistance to try new things. Your product can certainly be a great vitamin for many different people, but it is a pain killer for a subset of core users. Identify and target them first.
So many startups fail because they were too impatient and directly tried to have fun in the ocean. Your goal is not to please everybody and be available to everybody. It's better to have a thousand users who absolutely Love your product with a capital L, than 500,000 who like your product, use it once and then forget about it.
There are always exceptions to the rule but more often than not, you are better off artificially reducing your initial target market. Only target one language (English), one platform (iPhone users), one industry (for Storify we chose Journalism). etc. That does not prevent you from growing outside of that target market later on (brands and institutions started using Storify on their own). But limiting your ITM will make your life easier and it will give you the opportunity to focus your energy, learn and iterate faster.
The winner is not the first mover, the winner is the first that gets it right.