Creating too many backlinks too quickly can sometimes trigger Google's "spam alert" system, which can result in your site being "sandboxed" by Google. If that happens basically your site will be placed in limbo to give them time to review your site properly so they can decide whether or not it's spam. The end result: You won't appear in the SERPs for your keyword for many, many months.
If you're targeting a keyword with long term intentions, this isn't such a bad thing. Eventually your site will return and as long as your links / content don't look too spammy, you should reappear with a good rank.
But if you're planning to hijack an upcoming product launch (like I do), and you need your site ranked quickly without the risk of being sandboxed, here's what you do:
First, obviously optimize your website properly for the keyword(s) you want to target. I recommend to target at least two keywords. If you're using your home page to target both keywords, set up a sub page for each keyword to give you a chance at getting a double indent listing.
Next, write a high quality article related to your niche (or pay a freelancer to write it for you). Make sure to optimize the article correctly for your main target keyword (use it in the title, H1 tag, first and last paragraph, and also some variations using H2 or H3 tags).
Then, submit the article to Ezinearticles dot com and make sure to link to your primary site that you want ranked in the resource box using your main keyword(s) as the anchor text.
Now build ALL your links to this article once it's approved and live. Because articles can naturally receive thousands of backlinks quickly, it will appear to be natural to Google (or at least a lot more natural than building a ton of links to your site too quickly). And because you're linking to your primary site with a dofollow link, the article will pass a good deal of link juice to your site, meaning you should get a top rank in a short period of time, without the risk of being sandboxed.