Well ... the search engines are smart enough and they have not mentioned any particular number of such activities. Not only Article and social bookmarking can help you in getting top position in search engines. Perform all white hat techniques smartly !
Agree with you Maggyparker, make quality back links, use fresh content , this will help you in getting good reputation in SERPs.
First increase the quality of the contents of your site to attract targeted audience. You can measure it via looking at the bounce rate. If your site will be worth for your visitors then the chances are thy will spread it in their networks and efforts from your side will be reduces. This way your site may approach towards gaining high rankings.
There are no certain parameter for this ,it will depend on the current ranking of the website and do remember one thing about penguin update and do not use keyword stuffing in article and do only in natural way that you can get natural links only.
Fist of all it depends upon your keywords that you have choosen. Not only Articles and S.B but you have to take help of social media also. Social media facebook, twitter, linkedin, google+ also helps in generating high pr to a web-page.
Blogs, Classifieds, Local listings, Reviews etc. are also important terms to follow for generating Pr and helps in taking your website to top ten pages of the google.
I also agree that keyword is important. But the websites where you submit your articles are also important. Sometimes it gets better results for you to post an article to a site with high reputation than to ten sites with low reputation.
Yes sabrina you are right i agree with your comment but is only article submission is enough for taking the website to front page of google.
Don't you think that social media is also important?
Doing a regular social bookmarking and social media on high pr websites helps a lot in increasing backlinks and the reputation of a website.
Article submission and Social bookmarking are the best ways to improve your website rankings in google search Engine.you just need to do article submission on high PR Sites.You must do 10 article submission Per day on high Pr sites.