Great post - as normal Guido,
some great tips. I just wanted to add, that I started using isnare last month and am happy with them. I have also gone back to using submityourarticle.com and am over the moon with them. I use their article leveraging system and make sure that every article submitted to different directories differs.
I aim for it to differ by about 35% minimum, what I find is that when I do this a higher percentage of these articles are listed on google and the other search engines. I also submit separately to ezinearticles and am about to start submitting to buzzle.com.
On top of that I am a member of
http://www.ecademy.com and have just started to try and blog or at least reply to blogs and put up articles on a regular basis. Ecademy has a very high ranking in the search engines and articles and blogs on it tend to rank very well. I am fairly certain my articles on ecademy will rank much higher than even my articles on ezinearticles.
I am going to take a couple of your hints and try and implement those as well.