For each scenario there are ways of creating the fingers that are optimized for the output. However, in a fairly standard production, I've found the following to hold up nicely (Fig.08).
Fig. 08 - Standard edge flow
One of the most common missteps when it comes to making fingers is to simply leave them as extrudes down the length, with no attention or detailing in the knuckle. This way of construction leads to uneven deformation and gives you limited polygons to manipulate if corrective shapes are needed.
Joints and Joint Placement
Naming the joints in relation to the body is helpful when using the Paint Weight joint list. Having all your fingers prefixed with "_Fng_" - such as "j_L_Fng_Index_1" - will keep all your fingers together on the list and reduce the time spent searching for the others.
This can be modified to fit different workflows or preferences, such as naming the spine joints "j_Spine_0_Head", "j_Spine_1_Neck", "j_Spine_2_Ribcage", "j_Spine_3_Waist" and "j_Spine_5_Hips". This naming will list these joints numerically from top to bottom right and mean they will be next to each other on the list. Without those prefixes, you'd have to search up and down your joint list from "H" to "W" to paint the next joint.
To effectively mirror weights, naming the joints is very important. "j_L_Elbow" and "j_R_Elbow" can be mirrored using the Search/Replace option in Mirror Skin Weights, by searching for "_L_" and replacing it with "_R_".
Joint placement is another area that will take a good amount of practice and trial and error to get better at. Having an understanding of where the joints are anatomically will help, but it's not the be all and end all of where to place them. For example, there are 33 vertebrae in the human spine; however, you wouldn't want to put 33 joints in the rig for a multitude of reasons. But knowing where the spinal column is and how it's oriented to the body, will help you place joints more realistically.
One joint that is commonly misplaced is the clavicle. The clavicle pivot should be placed slightly to the side of the sternum at the front of the chest; however, many people starting out will place it along the centerline of the body or elsewhere (Fig.09).
Fig. 09 - Clavicle joint placement
As mentioned before, this placement of the joint is more anatomical, but may not suit your character. Joint placement can be anatomical or more centerline. Centerline works well for more cartoony deformation, involving squash and stretch. As cartoony characters can bend differently or more extremely, having the joints in the middle will keep the deformations even and consistent, while not favoring one side or another.
Overlapping Joints Affect Weight Mirroring
Another commonly misplaced joint is the eyelids, if you are using a single joint for each lid. If two or more joints share the exact same position, when the skin weights are mirrored to the opposite side, the results are not what you'd expect. With that in mind, slightly offsetting joints that overlap directly will remedy this issue (Fig.10).
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Fig. 10 - Mirroring results with overlapping vs offset joints