These days, building links naturally is the key to sustainable SEO. The fact of the matter is, Google are getting better and better at spotting unnatural links, so if you want to get to the top and STAY there, you really need to be careful.
Here are my two suggestions for how to make your links look completely natural to Google (or as natural as possible). I have used this simple strategy over and over again to get many, many #1 rankings:
First off, no matter what keyword you're targeting, find a Wikipedia page that's as relevant to the keyword as possible. In almost every case you'll be able to find one.
For example, if I were to target the keyword phrase "Motorola cell phone", I would pick a Wikipedia page that talks about mobile phones. (I do know the URL but can't post links yet!)
Once you've found a page that's as relevant as possible, now analyze their backlinks. I use Market Samurai but any decent backlink analysis tool will do.
What are you looking for here - and why?
First off: many, many people link to Wikipedia pages NATURALLY. So if you want your links to look as natural as possible, don't you think it makes sense to get links from the same sources they are and use the same or similar anchor text? Of course it does.
So what you're looking for here is, first and foremost, what type of links they're getting.
In most cases, Wikipedia pages get links from blog posts, blog comments, forums, and so on. The key is to delve deep, examine as many links as you can, so you can see ALL the different types of links they're getting.
Next, you want to examine exactly what kind of anchor text is being used. I wouldn't recommend copying their anchor text word for word, but it will give you some good suggestions to use.
For example, if I analyze the backlinks from the mobile phone Wikipedia page (I will post the specific URL once I have permission, but for now if you Google "mobile phone" you'll see the page at #1), I see the following variations of anchor text:
-mobile phone
-cell phones
-mobile phones
-mobile
-wikipedia, the free encyclopedia
-wikipedia: mobile phone
-mobile phone at wikipedia
-phones
-mobiles
-being tracked
-phone
-mobile phones.
-cell phones
-mobile phone information
-mobile telephone
Obviously "mobile phone" was the most popular anchor text (which is why that page is #1 on Google for "mobile phone"), but as you can see there are plenty of natural variations there. Because the simple fact is, when people create links naturally, they use all kinds of anchor text.
And that's all there is to it!
Pick a Wikipedia page very similar / relevant to your keyword, find where they're getting links from and what anchor text is being used in those links, and basically copy them. That way your links will look MUCH more natural to Google, since almost all the links created to Wikipedia pages are natural, user-created "votes", the type of links Google salivate over.