As someone with no such mental barriers you'll have to take take my words with a grain if salt. I'm certainly not ever looking to make purchase something that is crap/doesn't work/is useless. I do as much research as i can on the item, think about how I expect to use the item, and try to think about what may work and not work about the time.

If I can't come up with a strong objective reason to not get it then I buy it. Generally you can return most things so if I'm particularly hesitant about something due to too many unknowns I'll just make sure I can return it. Sometimes there may be a few but I consider that the price of the lesson.

There is also nothing wrong with asking the opinions of others if you know nothing about it and you know someone who might. People ask me about computer and electronics purchases because I have a lot if experience and can typically advise them of things they didn't consider.

What I don't do is ask people who know little to nothing about whatever the item is and then base my own opinion entirely on their uneducated one.

At the end of the day though you really just have to allow yourself to make mistakes. There's nothing wrong with that and is often the one if the best ways to learn something.