Hex editor help

hey guys,
I've got a hex editor but I'm not too clear on how to use it. I know all the program specific features like, how to load files, RAM, drives, edit data, etc. But when it comes to interpreting the data, I'm clueless. Now I know that the data is different depending on what you're editing so I was just hoping that someone could at least give me some general tips on how to interpret the data and probably anything else you think might be useful.
And just for the record I'm not particularly interested in using it for microprocessors.

Thanks in advance

I doubt you will find this helpful.

The data you are editing is 100% context dependent. It can be anything including the hog futures from 1964.

If you know what the data is and what format it is in you have a place to start.

We do not have a clue and all we can do is guess.

If you're not clear on using a hex editor - STOP NOW. You can do more damage with it than without it if you don't know what you are doing. With that said, as mentioned by 3v0, knowing the format of files and/or other structures is absolutely necessary. If your hex editor has is (and I have yet to see one that doesn't - but if yours doesn't, bin it and find another), turn on ASCII mode so you can see the data you are editing side-by-side with the hex values. Finally - if you are hex editing disk sectors or memory, you better absolutely know exactly what you are doing; corrupting a file is one thing, corrupting a disk structure or crashing your machine is an entirely different can-o-worms...

ok, just to appease everyone I'm not going to monkey around with my computer's system or anyone else's for that matter, I'm quite aware of the dangers. Now with that being said, I've heard of people who've modified firmware using a hex editor and frankly, this is what I'm interested in doing. I'm thinking of experimenting with the firmware of an old cell phone that I have lying around, so I was just wondering how exactly do these people know what they're doing? And what kind of information about the device(phone) do they need?

A cell phone is a micro controller with a radio and nice display. The firmware is the program it runs!

Unless you can find info from people who know what they are doing you will have about the same chance as monkey with a typewriter.

Programing esp microcontrollers can be a lot of fun but you have to start on chapter 1.

Your effort at appeasement has failed.

ok then thanks