Miklos,

I could be, but if you are not aware of the other companies business practices, or better yet, what is their level of expertise when it comes to getting the marketing done, and done right, say for Google. IF you are not aware of what is currently working in Google, then you are not doing your clients any favors, so I would definitely keep that in mind.

Other than that, I also think it is a good idea to find someone who compliments your work, or has the skills that you lack, so then together you make a great team.

Try to always think of what would help the overall system to help the clients in the best way possible. Do your homework and find someone to team with that can add to your skill-set to ultimately help the clients.