The Best approach to this is just HAVE FUN! If you make a job out of it, your going to get a sour taste in your mouth. Maybe that's why I still love my job as I look at it as a hobby/game more so a business. Anyone and everyone is going to make a mistake. Look at the mistakes, study them and then correct them. Don't dwell on the screw up or the imperfections, nor worry what some dumb-ass is going to say about it. You WILL be your worst critique! Just remember it's a start. I myself have hurled projects across the room, then I laugh as all the other sewers duck and cringe, LOL!!!!
As mentioned, visualize the finished project, gather your dimensions of what you wish the pouch should be, add allowances for hems, stitch widths, thickness of material if there is to be dividers or optional components on the gear itself to be placed in. Take that info. and draw it down on thick paper for your pattern. A ruler is your best friend. Include your grommet holes, snap location, or any other hardware that may be used. Also take in factor of stitch shrinkage. Then cut out the outline of the pattern. Once cut out, fold the pattern to form the pouch and then study it and remember to take more measurements to verify the fit. When satisfied, transfer the pattern to scrap material and sew it up. Sewing in a manner of looking at the pouch from the back to the front in some cases. Your going to forget something and make mistakes, No question about it. Then have fun sewing and be prepared to rip out stitches multiple times.
Once sewn, take a step back and observe what you have accomplished. Could you have done better? Hell YES! But it was a learning experience none the least. If it looks good enough for now, take it out and put it through the pace. You will always feel that you could have done better. So do not get discourage as you can always start all over and incorporate the lessons learned into the next project. If you cannot live with the fact that it sucked, I'm assuming you own a gun. Shoot that piece of crap and you will honestly feel much better. At least you tried!
No need to to get all upset if you fail. Just feel good that you tried. If your suspenseful, Post some Dam pictures!
Gene @ HSGI