What books should I read before beginning Masaki Kashiwara and Pierre Schapira's "Sheaves on Manifolds" I am a beginner trying to learn about sheaves. I am trying to read Masaki Kashiwara and Pierre Schapira's book "Sheaves on Manifolds", but I find it is not easy for me to understand.
What other books should I read first, with little knowledge about abstract algebra and homological algebra?
 A: The book of Kashiwara and Schapira is quite focused and technical. I won't recommend it as an introduction to sheaves, since the abstract language of sheaves and homological algebra is most useful when you already know a big class of examples.
If you're planning on hitting algebraic geometry one day, it could be a good idea to start with reading about it now. Any technical book, e.g. Hartshorne or others suggested in this MO question
will contain such material as sheaves, functors, derived functors, Verdier duality, etc.
There are also better places to learn about D-modules and related stuff; e.g. note Kashiwara and Schapira’s book says:

(p.411) Although perverse sheaves have a short history ...

and, indeed, 30 years later there are quite a few introductions to perverse sheaves that are easier to read.
I don't know about microlocalization, perhaps this topic should be indeed read from Kashiwara and Schapira.
Now we'll be able to recommend a more specific text if you tell us what exactly you planned on reading Kashiwara and Schapira for and where you get stuck!
A: I personally won't recommend Bredon's book, rather Iversen's "Cohomology of sheaves" (especially if you are interested in the topological aspects/applications of sheaf theory).
There is also Dimca's "Sheaves in topology". However I should say that the epigraph to this (very good) book is "Do not shoot the pianist", and maybe not without a reason.
If you are more into algebraic geometry, then you should read chapter 2 of Hartshorne.
A classical reference is Godement's "Topologie algébrique et théorie des faisceaux".
Prerequisites for all of these are some algebra (the definitions of a ring and a module, basically, but if you've never seen complexes before, you may find the presentation a bit dense in the beginning; you'll also need some commutative algebra if you are reading Hartshorne), some basic general topology (and also some theory of smooth manifolds, e.g. partitions of unity, in the case of Iversen's book) and some category theory. You could just start reading Hartshorne or Iversen (depending on what the goal is) and then look up categorical notions that are unfamiliar in MacLane's "Categories for the working mathematician" or on Wikipedia.
A: Assuming you already know undergraduate algebra (and maybe a little basic homological algebra) already, the book Methods of Homological Algebra by Gelfand and Manin is a good source for the kinds of things in the first chapter or so of Kashiwara-Schapira, i.e. derived categories, derived functors. I can't remember how elementary its sheaf theory is, but a little background in sheaf theory wouldn't hurt either. Swan's book is probably a kinder starting point for sheaf theory then Bredon.
A: I like: Iversen, Cohomology of sheaves
http://books.google.com/books?id=JTAZAQAAIAAJ&dq=Iversen+Cohomology&hl=en&ei=gScvTO6_JpqqsQaquL21Ag&sa=X&oi=book_result&ct=result&resnum=10&ved=0CFIQ6AEwCQ
It serves as an introduction to sheaves and their cohomology without requireing 
much background. Applications to topology and algebraic geometry are
explained. Morover it has an appendix on derived categories.
A: I think, the first volume of Harder's Lectures on Algebraic Geometry contains a nice and balanced account of sheaf theory and the cohomology of sheaves. Besides the title, it is not really a book about algebraic geometry. Instead there are many examples from algebraic topology and Riemann surfaces. One should although note that the book contains many typos. 
A: There is the book by Bredon called "sheaf theory" but I'm afraid it may not be better but have a look. 
Of course if algebraic geometry is your goal then you can learn it directly from Hartshorne or Ueno.
