Ask HN: How do you decide to go ahead with your side project?

I was thinking about working on new project. In a nutshell, it would be something like "uber for translators". I have done some research, feedback was mostly positive. (more about the project in my post from /r/beermoney https://www.reddit.com/r/beermoney/comments/8dq1eg/would_you_join_uber_for_translators_to_make_extra/) Unfortunately, there seems to be already existing projects which do the similar stuff. I still think there could be a potential with the right execution and focus. I was also thinking I could at least bring this project idea into Czech Republic (my home country) and make it with local focus only (global project would be preferable for me tho). I would like to get some ideas/advices on this... how should I decide If I should go ahead with the project and spend more time on that? Any other ideas how to validate the idea beforehand? What are your expirience? Any feedback welcomed. Thanks in advance. George