For a short city walk, a bag should carry the kit you intend to use rather than every item you own. Begin with the camera, one lens or a small lens pair, a spare battery and a card. Add water, glasses or other personal items only if the bag will realistically hold them without pressing against the equipment.
Check access with the bag on your body. You should be able to retrieve the camera without opening every compartment or placing the bag on the pavement. A zip that looks convenient on a table may be awkward when the bag is worn. Try the movement with the camera strap in place so that access does not require an insecure handover.
Fit the dividers around the actual equipment. The camera should not slide freely, but the padding should not squeeze buttons or bend a lens hood. Keep hard loose objects such as keys away from glass and displays. A water bottle needs a separate secure location where a leak cannot run directly into the camera compartment.
Walk with the loaded bag for more than a minute. Notice whether it swings, pulls one shoulder or rubs against the hip. A wider strap may distribute load differently, but comfort depends on the total weight and your body. Adjust the strap so that the bag remains reachable without bouncing excessively as you move.
Consider the route rather than a generic travel scenario. A crowded market favours a bag that closes securely and stays close to the body. A quiet walk with frequent camera use may favour quicker access. Neither situation requires advertising the contents. Keep the bag closed between uses and avoid leaving it unattended while composing a photograph.
Check what the maker actually says about weather protection. A fabric that resists a brief splash is not the same as a sealed waterproof container. If rain is likely, carry suitable protection and know how to reach it without unpacking the whole bag. A cover should still allow you to carry the bag securely.
After the walk, note which items were used and which caused inconvenience. Remove unnecessary weight before the next outing. A useful small bag encourages you to keep the camera available while leaving enough attention for the street, rather than making every photograph an exercise in unpacking and repacking.
