As someone who has an interst in zombie fiction- in TV, film and the written word, I have read several zombie novels as well as several stories here on fictionpress (as well as played several video games). While many stories on this site have potential in terms of plot and writing style (minus the useual grammatical errors one would expect from those of us who don't have a beta), others suffer from what may be termed "confusion," for want of a better term, on several areas that make me, as a reader and self confessed zombie fan, feel uncomfortable after several paragraphs, or even chapters.
This "confusion" may be broken down into three broad areas. Zombie types, characters and environment. Each will be discussed seperatly, but please be warned, there may be some overlap. These will be marked by the star sign- *.
There are three main zombie types in fiction, one of which does not play a part in modern fiction, but can be found in older works.
One) The Voodoo zombie. The original source of the word zombie. Voodoo zombies are living people with brain damage* who are under the effects of voodoo zombie powder. This powder renders the person unconcious and slows their bodily functions down to such an extent that trained medical professionals pronounce them dead. They are buried, and while buried, run out of oxygen, thus the brain damage. They are then exhumed, and put to work, useually by the person who used the voodoo on them. They are easy to control and listen to verbal commands. They can communicate at a basic level. Personality traits may or may not be apparent. They feel pain and can remember the source of the pain- if they are burned, they know not to go near fire again. These are the main differencences between them and the other types of zombies.
*Been alive may also be a trait of the "runner" zombie, while brain damage may appear in all forms of zombie. However, voodoo zombies are the only type where their been alive and suffering brain damage is guaranteed, and the only type of zombie who will only attacked if provoked, therefore, acting in self defence.
Two) The "shuffling" Zombie. Of The Walking Dead fame, and who also appears in the novel World War Z by Max Brooks. The best known of the three types. Certainly the most visually recognised and mimicked. As the name suggest, these zombies shuffle along at a slow pace. This is due to the fact that they are dead, and rigour mortis has begun to set in. They owe their genesis to a viral outbreak* or to some unknown source. They are dead and slow moving, with their main fear points being their sheer numbers and their relentless drive. They are missiles and you are their target. They will never give up. They will hunt you until you collapse from exhaustion, until they loose "sight" of you, or until some other poor, unfortunate victim stumbles into their path. Their stamina means they can continue hunting you or beating on a barricade until their muscles decintegrate. Generally, they have little to no intelligence, and are driven by the most basic of insticts and needs- the need to feed and they are drawn to sound and other outside stimuli*.
* A virus may also be the reason for Runner Zombies. While some runner zombies show signs of wanting to feed on human corpses, most are suffering some sort of maniac rage, as seen in the movie 28 Days Later. The reaction to sound and outside stimuli will be discussed further in characters, but for the moment, think dinner bell.
Three) The Runner Zombie. Made famous in movies such as 28 Days Later and The Crazies. As the name suggests, they are fast moveing, able to run at amazing speeds and sometimes, performs feats most ordinary people would not- such as withstand multiple gunshot wounds before dying. Generally living people suffering brain damage due to some "viral outbreak," the brain damage means they are insane or operating at the most basic levels. The brain damage useually suppresses the areas of the brain responsible for pain. Their main drive seems to be their desire to kill, not feed upon, humans. Their main fear factor is their speed.
Further Notes: As is evident above, both the Runner and Shuffling Zombie are immune to pain, but for vastly different reasons (as death means the nerds are not working in one, and brain damage means the other does not register it). As a general rule of thumb, the motivations between these two zombies is different (homicidal rage versus desire to feed). As can also be seen, the voodoo zombies only desire is to serve, as was the intention of the person who used the voodoo zombie powder on the person in the first place.
For every author, the choice of character is entirely their own. However, no matter how unique you wish to make your character, there is one basic rule to get them past their initial encounter- if they draw attention to themselves, they are dinner. All types of zombies are drawn in my external stimuli- sight, sound, smell. If, in an initial outbreak, your main character is running around screaming, they will be seen, they will be heard, they will be followed.
Depending, of course, on where they are located. The risk of been seen, heard and followed separately to any other panicked person in Times Square in broad daylight, for example, is less than if they encountered a zombie on a dark street in a small town late at night. Those characters who survive the longest are those who know to stay hidden, stay quiet, but can run the fastest, react the quickest and aim the best when (and IF) the situation calls for it. In other words- they don't draw attention to themselves unless it necessary.
Of course, for many, for the sake keeping the interest of readers, a confrontation is needed at some point. This could also occur with other survivors- a tense standoff for example.
The enviroment can play an important part in your story. Extreme heat can leed to rapid dehydration, slowing your characters down. Dampness and cold leed to ilness. Both increase the risk of your characters dying. Zombies aren't the only threat in a zombie apocalypse. Remember, in such an apocalypse, any first world country rapidly becomes a third world country.
For now, thank you for reading. These were just some basic observations on my part, and I will be more than happy to expand on them if requested. I will, of course, be putting these observations to the test in my own zombie story. Keep an eye out.