Been reading a lot about decision making lately because, too often, I just feel like I can't decide. There are some interesting things I've learned. Here are my favourite researched insights and tips

The invisible villain: confirmation bias.
Hunting for self-serving information that confirms our initial assumptions.

Look out for it the next time you're asking what external display to buy (apparently that's what a lot of ppl on twitter do these days )

Here's a tip : When reading product reviews, prefer the 3-4 over the 5 ones.

They are often more down to earth, honest and give realistic expectations. In 5 star reviews the product is often too "perfect".
1-2 star reviews are mostly about broken shippings.

Next time you need to decide, consider your "Opportunity cost".
Ask yourself what else you would give up when you make a certain decision. Instead of buying your next expensive gadget, you could spend that money on a nice trip with your spouse.

If you really have to buy that thing, but still can't decide between 2 products, ask what value the remaining money could bring if you took the cheaper option

Take the amazing sound system for $500 or the really good one for $400 and use the remaining $100 for music to listen to

To gather more trustworthy information, ask disconfirming questions.

E.g: In a job interview, ask how many people were hired 5 years ago? How many of them remain in the company? Who were the last three that left the company and why?

To overcome short-term emotions, which influence our decision making heavily, attain some distance using the 10/10/10 technique:

How will you feel about your decision in 10 minutes from now?
How about 10 months from now?
How about 10 years from now?

That's it!
Of course, there are many more methods, mental models, tricks and things that help making better decisions.

Hopefully these give you a good start to explore this topic!