How will you know if your idea is a success? You don't need fancy growth charts, milestone maps, and achievement metrics. Success is different for everyone, but there is some goal or milestone that you'll feel like your idea was a success when you reach.
What is that for you?
Actually measure something
This has to be said right up front because all too often, we forget to do this at all. I know I'm guilty of this sometimes too. In a rush to get the product or service out there and help people, we forget we should know how we will quantify our success.
The nice thing is you can evaluate whatever you want. This is your work. What success means to you for this project is different than what others need. In fact, this project of yours is probably different than other projects you work on.
But this is a nasty problem here too. Having personal responsibility and desire actually to assess something. In some ways, this is the definition of success -- the challenge to take action and calculate the things that drive your work's success.
Your own measures
While you can use whatever you want to measure whatever you want, what will you use? The paradox of choice is a real problem sometimes -- and this could be one of those times.
There are so many things to think about and factor into what you will evaluate. Let's see if we can help you choose what will effectively determine if your idea has succeeded (for you).
First, you should put some time into thinking about what you need to consider your idea a success.
What do you need?
Do you need a certain amount of profit? Audience growth? Feedback? Outside investment, maybe? Or learning situation?
Perhaps your work isn't about money or fame. Instead, it could be a small experiment to test a theory. The goal may be the experience of completing it. Your measure of success here could be as simple as were you able to complete it?
You might also think about how long it took you to complete it, or if it is something you can turn into a repeatable process.
If you decide your idea must turn a profit, you'll probably want to measure at least a few minimum things like operating costs, total sales, marketing costs, conversion rates, where and how many leads you get, etc.
This is an area where you'll find many resources online to help you calculate the success, the profitability, of your work. Something like ProfitWell if you have recurring subscriptions (and the metrics from ProfitWell are free).
If you seek to make more people aware of your work, you might think about return visitors, page flow, email list opt-ins, or social media growth. Consider various engagement points, such as survey votes, video likes, comments, and other forms of active attention.
Measuring this can be as simple as reviewing the metrics some of these services offer you and writing them into a spreadsheet to track over time.
While many of these services will show you data over time, I think it is important to aggregate your total audience growth into a single source where you can review it from time to time.
You may be most interested in the feedback you can get when others use your work. Here you will likely want to consider the amount of feedback you get versus the outreach to ask for it.
Maybe you'd like to have some sentiment analysis and a goal for a certain amount of positive feedback. Or a turnaround time for your customer service to answer negative feedback.
Put yourself in check
You're the owner of your own ideas. While this is a fantastic position to be in, it also means you're almost too involved to see certain aspects of your idea in total.
Being the boss means you have to lead and actually do the work to determine your ideas' success.
Don't attach yourself too much, be objective
I know, this idea is your baby. You worked so hard to bring it to life, and now people can see it. They're going to have opinions -- sometimes opinions you don't like.
It'll hurt. But this is just one example of why you should learn to understand the idea you made. It is not you. Don't take everything personally.
By being objective, you'll actually listen to the feedback you're getting -- whether than it opinions from users or data from your measurement tools. If you don't objectively listen to the feedback with an open mind, what's the point of measuring success?
Follow a plan
When you understand what you want to measure, build a plan with the steps you will take to measure, how it will be measured, why you're measuring, and the ways you will review the measurements to determine the success of your work.
Reminder: this is your work. There are massive, corporate, lengthy processes for measuring projects. Huge structured projects on their own almost. You don't have to follow some industry-standard process (unless you do, but you know if you do).
Build what you need to follow to measure the success you want from your idea.
Stay away from feel good metrics
While it is nice to see all the big flashy numbers such as page views, email signups, etc... you should be aware these often don't actually impact your idea.
You need to find real data to follow. Things like conversion rate, follow-up rate, page flow, goal conversion... whatever it is, directly impact what you consider success for your work.
You could use an analytics tool like Google Analytics. I Fathom Analytics because they care about visitor privacy -- you can easily set up goals that will help you track when users do things you want them to do on your sites.
Step back and look at the big picture
Coming back to you... that is, you being so close to your idea you forget to look at the big picture. Step back, take the time to actively think about what your idea must look like to outsiders. What is it they think is what makes your idea a success?
You might also want to consider your competition and compare your success with theirs -- maybe find the gaps where you could learn from their efforts and adapt (not steal) for yours.