You need a small carry case for your outside activities. The problem is that such a pouch has a specific shape and layout that has to match the equipment that you carry with you on your days out. In the case of a Saturday trip to local trails for a day's walking with a picnic in between, errands to do afterwards and a car to travel in, a list of items such as phone, keys, glasses, small first aid kit, sun screen, a snack and charging cable would be a useful load to carry. Such a list does not need a large carry case but a good pouch to protect your gear, to make it visible and to be comfortable to carry when things don't go as you had planned.
Start with the day, not the pouch
Start with your day. Start with your contents. Then pick the best pouch. A pocket for phone and ID and/or a sealed pocket for keys is essential. Once you have laid out your contents to organize then you can add in the 'occasional use' items like headlamp, charging cables, blister care etc. Then see if you have anything left over to add to your organizer.
When packing for a trail-and-errands sort of day, the essential items are identification, keys, phone, personal hygiene articles. The occasional items are a headlamp, compact recharger, blister care and a small multitool. It is useful to design around the occasional use item, otherwise you will carry a bulky pouch every day.
Take note of the actual form and number of items that you intend to carry. Flat items like credit cards, and cables, like for instance your recharging cable for your mobile phone, would best be stored in sleeves or elastic loops. Small bottles, a glasses case, or a bandanna rolled up, will require space of some open width. If most of your gear is flat, then a wide organizer is more suitable than a deep, 'tactical' type pouch which would probably just end up in a messy pile.
Match the layout to how you reach for gear
It's all about reducing the number of searches to find your goods. More than one pocket is better than one large cavity and prevents stuff like snack wrappers to hide your keys in between. But don't go overboard, excessive pockets will result in the pouch not being able to handle deviations from your planned load.
For this trip, it would be good to have the phone and ID in a safe spot, the keys in a separate and zipped up area, the first aid items in a spot where you can get to them without having to take everything else out of the pouch, and cables and battery packs in separate, small pockets so that they won't get damaged by sharp objects.
Look for small design details that aid one-handed use of the pouch such as a grip-able puller on the zipper, a mouth opening that enables viewing of the pouch's interior and a base that will remain upright when the pouch is opened.
Decide how much protection the contents need
Be aware of the amount of protection your items require and choose a pouch accordingly. The phone, your cards and your spare batteries probably need more protection than your packet of tissues. And if you're going to be storing your pouch in a daypack then probably the outer of the pouch is all you need to consider. But if you're going to be leaving it on a damp bench or moving it from vehicle to vehicle then easy cleaning of the pouch must be a priority also.
A water-resistant fabric does not equal a waterproof container. The seams, the closure, the zipper, all must be evaluated in relation to the promised level of water-resistance or indeed full water-tightness. Even then, note that the maker's recommended cleaning method is likely to involve wiping with a damp cloth and then allowing to dry. Storing a waterproof pouch in a wet state is a sure way to make its zipsticks stiffen and fail within relatively short order.
Furthermore, note that also the material used for a pocket has to be easy to clean. If the fabric has a smooth surface then it can be cleaned with a brush or wiped with a wet cloth. If the fabric has a rough surface then it can hold a lot of dust and it is hard to clean it. For cleaning also pay attention to the seams, zippers, and other openings of the pouch. Follow the washing instructions of the maker and avoid storing the pouch while it is wet and spot soiled. After a sandy or muddy trip check the zippers for any sign of stiffening.
Choose carry options for the way you move
Consider the different ways you will carry your everyday carry items: worn, packed, clipped to, or left in a vehicle. A pouch designed to be carried in a daypack is likely to be too large and cumbersome if designed to be worn around the waist. The only advantage to a strap is to provide a different way to carry the same item, potentially adding bulk to an otherwise compact pouch and even more weight to loose straps and other hardware.
A packable trail pouch would ideally be a wide organized pouch to store flat items like a wide bandanna, glasses case, etc. A wide pouch can also allow for easy viewing of items such as sunscreen, snacks, band aids, etc. within the pouch. For a picnic or short day hike a pouch with a handle, clip, or attachment point would be ideal to wear as a pendant around your neck.
Test the loaded pouch in all your different clothing items and inside your various packs before you purchase it. A pouch that fits in an empty pocket when it's empty may become a bulky annoying addition when it's filled. Also check that the attachment can be removed or that it can be secured when not in use.
Build a loadout that stays manageable
Once you have chosen the right outdoor organizer, load it with the same items in the same order every time so you can verify that you have all of the necessary items for a trip before you leave. Also, remember that it is easy to overfill an organizer for everyday trips, and there should be enough room for one or two additional items for unusual or extended trips.
The scenario for a short trip out may change from a short 30-60 min walk to a longer 2-3 hour or all day trip. Therefore for a short trip out, a small amount of space for a few extras could be allocated, possibly using a small removable insert or perhaps an alternative configuration.
The organization and other features of the pouch will get worn and perhaps even dirty. Check for grit in seams and clean the pouch as needed. Test all zippers, especially closed ones, and check seams for wear. Discard used up, damaged, or outdated items such as bandages, medications and food. Make sure to store sharp items such as scissors and knives in protective sleeves and in separate places from electronic items like watches, cameras and lanterns.
By starting off with the things you need to carry for each of your out excursions, you can arrive at a very simple outdoor pouch. Add in some space for dirty items, weather, clean up, transport, and the many different trips you go on, and you will find that you use your new outdoor pouch frequently for everyday organizing.