Basic questions about Link Building

Hi guys

I am going to start on my first link building exercise for a new site.

I have never done this before and I have some pretty basic questions I'm afraid, I'd really appreciate some help so I don't get it wrong!

I am going to start with some guest posts on my clients blogs, and allow them to guest post on mine, these are a couple of questions I have:

1. How many keywords should I link to within a blog article? I don't want it to look spammy but would say 2/3 links back to my page be enough in a 2/300 word article?

2. Should I write a different article for every blog post, or is it acceptable to copy/paste the same one a couple of times?

Where do I go after this, I am not sure where else I can backlink to. I have setup social media accounts and will tweet some great money saving deals every day which will also auto post to facebook so hopefully that will create some if people share them (I do need to get some followers and like's on my pages first though!)

I just want to do it the right way to ensure I don't get Penguin slapped. I read a lot about Web 2.0/High PR sites but I don't really know what they are or how to find them, let alone posting a article to these sites.

Any words of wisdom would really help me out!

Thanks