A website has to communicate this to all search engines that how credible and reliable it is in order to get high traffic.  Majority of the people use search engines for their searches and queries, your website has to be on top results of search engines to be noticed.  Why would search engines take you on top? A very effective factor is link exchange.

You need to make sure that the sites which are linked to you must be related to your industry otherwise the impact would be missing. Targeted traffic is generated if a site recommends its visitors to go and have a check to some other site about the information he is looking for. It is important to have back links from high PR (page rank) sites.

SEO Services Company must not use spamming to get back links, this way a site can be banned.  Blog is a very effective way of increasing traffic too, please visit Ways To Increase The Level Of  A Website Traffic  (Part-5) to know about blogs.