Some people make the mistake of equating SEO simply with tweaking a website’s code and contents in order to rank well with search engines. While this is where the bulk of the work goes to a good SEO knows that there are plenty of other factors that affect their work as an SEO. One of the factors often overlooked by people is web hosting.
Web hosting is NOT part of the work of an SEO. However, the hosting of a website can affect its ranking with search engines aversely IF it just so happens that you use a hosting site that has been identified by search engines as spammers. Of course, the hosting site itself would not be the spammer but websites hosted by them have been or presently be full of spam. This will result in a page rank for you even before your start SEO making your SEO efforts futile.
To ensure that you don’t have any problems with your IP address you can either purchase your own server and maintain it in-house(which is not an option for many) or simply request your hosting service to provide you with a dedicated IP address that is NOT blocklisted. Note that this might not be possible for some hosting services if they no longer have lots of IPs available and they might just say that they have given you what you asked. To check out whether your IP address really is good check it using the free trial of the Spam Database Lookup at DNSstuff.com.