.com and .net
 

Im thinking about buying the .net of one of my site domains Yet was thinking about using it as a blog to feed the .com of that site...will google index it well or penalize both domains?

If it is going to be a new domain with its own content then I do not see why Google would penalize you.

I was hoping not..Example: www .xyz.com , the content for sale.... www .xyz.net a blog driving traffic to www .xyz.com

com. the domain is always the best!

for a new site and after hard work on SEO, one of my kw is on top on all Important search engine

Yeah..I went with a differnt domain .com name..

I would add the blog to xyz.com/blog or create the subdomain blog.xyz.com , google would treat the sub domain as a new site

I think .com is the best.

.com is the best well known and trusted domain world wide.

.COM still the best 2nd option is .net