Very interesting information on SEO, it seems that its a bit of a no pain no gain exercise. How can you measure performance?

I.e. if i'm spending hours trawling the web to get inbound links, articles pointing to my site etc.

How can anyone know what's helping their sites SEO or is it just hit and miss which links that google likes and which are a waste of time.

Any advice would be appreciated.

Cheers, Ady