how many bookmarks should be done for a keyword for new website by which it is not called spam bookmarking.
Approximate 15 to 30 websites are enough for bookmarking of new website. But always try to use most of famous bookmarking sites that should have high pr & alexa rank.
You can do 20 - 30 Social Bookmarking for a keyword daily, You can target 4-5 Keyword of your website daily, Then your Number of daily total bookmarking is 100-125 daily. i.e 20 Bookmarking of 5 Keyword. This is not Spamming...
If your website is new then submit your website link in high PR bookmarking sites such as Digg, stumble upon, delicious, etc.
For the new website, the best thing is to create 5 bookmarks per day with several directory submission. build link slowly. It should look like natural link building. If not you'll get penalized quickly. If you couldn't do drip feed bookmarks, sent me a PM. One of my friend is doing that.
Please share some useful high PR site.. what are the strategy to be used such that it does not get spamming.
I think, a lot of links increasing in a short time is not good for a new site. You can do some social networking sites, google likes them.
It is good to provide the social bookmarking to the new site based on Google's latest penguin update. As per the latest penguin update, if you focus home page URL on all the social bookmarking sites, it will be spam, so you will bookmark each page(inner page) on those bookmarking sites. It is enough to provide 100 to 150 bookmarks for a new site.