Unlike Steven Drennon, I feel that in general "and/or" is not good writing, both in fiction and non-fiction.
While writing is not spoken language, it is generally intended to be read – by a "silent" reader, who, as studies have shown, will nevertheless usually subvocalize and stumble over "unspeakable", purely written constructs; by the author in a public reading; by a professional voice actor for an audio book.
While "and/or" is common in the convoluted styles of technical and business writing -- writing that many users of this site are probably intimately familiar with and which has distorted their natural feel for language --, it is not something that most people usually say.
The construct "and/or" hinders understanding in that the reader (or listener) has to think back on the previous passage and deconstruct the whole sentence and attempt to understand what the two parts being connected actually are, what the two versions of their connection are, and what it means that the author finds himself unable to decide wether the conjunction is additive ("and") or disjunctive ("or").
To take your example, the two versions of your sentence are:
... and try not to slow him down and get killed.
Here, getting killed is a consequence of being slowed down.
... and try not to slow him down or get killed.
Here, "or" lists a series of increasing alternatives ("you may win / have to pay one, two or [even] three hundred dollars").
As you can see, in your sentence the "and/or" does not mean "either A, or B, or (both A and B)", but "either (A leading to B), or (A or even A++)", which, in my opinion, isn't a very meaningful statement and a sure sign that you don't really know what you want to say here.
Therefore, in general, it is better to think about what the idea is that you want to express, and write it out in full sentences.
That said, of course there is experimental fiction writing or fiction writing that emulates non-fiction writing modes (such as internet slang) which utilizes glyphs ("
Doing it Wrong™") spelling ("
n00b"), non-narrative text ("
imsorry.jpg"), or layout (such as tables or lists) that are not usually found in narrative fiction.
"and/or" might certainly be appropriate in such writing, especially if it is humorous and/or fits the character of the story's narrator, but even then you need to be sure that you use it where it makes sense and actually says what you think it does.