When should I use parallelism? [closed]

Question

After asking this question, I got to realize that parallelism may not always be good.

So far I can see that parallelism (under c#) is

• A little complicated code-wise
• Will probably insert some concurrency complications
• Will not always be faster

I am looking inside parallelism because I want to make existing and new applications work faster, but now I see that it is no silver bullet.

When should I use it? are there any best practices? Is it just a waste of time in most cases? Is it suitable for a specific kind of applications?

I am looking forward for your insights on this matter.