You ARE GOING TO FAIL! Yup! If you try anything in life, sometimes you will fail. And you'll have to deal with it, Overcome and fight it. THis will allow you to move forward. Obviously failing the same thing over and over again is a big fat waste of time though. So I disagree with those people who say that it's good to "fail often."
Sure, If you don't know how to deal with failure, It's good to learn as soon as possible. But once you fully grasp the consequences of failure and you know how to learn from it quickly, It becomes this good thing that can help you.
Here are tips to help you fail less frequently so you can achieve your goals fast.

Record How You Are Doing Things

DATA DATA DATA DATA!
I can't emphasize that enough. When you pay attention to what is happening and how, you learn about what you can do to improve and fix things. When you don't pay attention to data, you are more likely to be confused about why you are failing.

As someone who is self-employed, I regularly do "Time Audits" On myself. Where I force myself to write down what I did for each hour every day for a few days.
While this sounds like a time-consuming thing, It's not, And you'll get a good idea of how you are wasting time real quick.

Also recoding things, in general, will allow you to expand in areas that are WORKING!
There was a specific "type" of shirt I was selling a lot of, But I was unaware. Once I looked at the data, I started making more shirts related to that topic. As a result, I have increased my sales by over 30%

There Is Almost ALWAYS A Way

To record what you are doing! So get creative and figure it out. Sometimes it won't be 100% Accurate, But if you can get it mostly accurate. It will make a difference.

Look At The Results

Duh!
Surprisingly though, We sometimes collect data then forget to look at the results. The results are going to tell us exactly whats going on, And that makes a big difference. So Don't hesitate to spend some time looking at the results.
There is no point in collecting data if you aren't going to use the results to help you.

Review & Make Changes

Reviewing your data and coming up with an action plan is important for continuous growth. Otherwise, you'll just naturally keep doing the same thing over and over again.

We Never Know What Will Work!

It's almost impossible to predict your exact results from something. SUre we can see other people do it, Then hope to get the same results.
But ultimately things may or may not workout. And it's better to try something that isn't perfect rather than something that is.

I love this comparison with Steemit and Synereo.
They released an "imperfect" version of Steemit. And now they are making improvements; I respect that so much more. Than what Synereo is doing, And they are taking forever to release the "final" product that may or may not do well.
Sometimes you just have to take that chance. This reminds me of the quote, "Better to ask for forgiveness rather than permission. "

Revise QUICKLY!
When you drag things out, They get expensive.
And no, I'm not just referring to money, But also time. So do what you can to make adjustments quickly and try to learn everything you can. This will cause you to fail a little more frequently at first, But you'll get to the success much faster.