Increase Serps / Blog Farm?

Ok,

I currently have a legit website quite large & established for about 5 years in a certain niche,

I rank well for most of the related keywords but there are a few im not ranked for,

My question is should I?

1. Increase Surps
Should I work on increasing surps on my exisiting site and forget about a blog farm?

e.g. use Xrumer directly and other tools for bookmarking / promotion?... Any Suggestions?

*Im new to blogging by the way*

OR

Build a blog farm relating to additional keywords that im not ranked for, and possibly use a cloaking method to direct traffic through?

OR

Buid a blog farm, again relating to additional keywords that im not ranked for but just link to my exisiting site and dont use a cloaking method, just fill it with content, spin it etc..

and possibly use things such as cookie stuffing to hopefully increase my affiliate earnings for the main program I promote?


Also when targetting a keyword, what sort of competition should you stay below e.g. 2mil results? or much less?

Thanks for your time.