How to choose the link?

When I need a link, to improve my ranking on google, I look the google pagerank and decide if I can ask for a link exchange.
But on Yahoo how do I have to choose link partners?
(Of course I have to choose related websites: both on yahoo and google, but among them how do I decide the best?)

that means you choose random links on yahoo?
nobody knows?

given that PR is usesless in most cases, I choose to check various factors including PR.

(I do these for homepage as well as the link page)
1. SERP on Yahoo and Google for atleast 3 diffrent phrases.
2. backlinks on Yahoo and Google
3. google PR

If i do this, I will improve on both search engines.

I do the same, but let's focus on your point 2)
How do you choose "backlinks on Yahoo"?
You know, on yahoo pr does not care.

The order in which Yahoo shows backlinks is always the descending order of the rank on Yahoo. So it is much clear than a PR.

If you want to estimate PR of a site on yahoo, check its backlinks. See where the site's home page and other pages appear. Also check backlinks of sites the site-in-question links to, and then see where this site comes. That will give u some idea.

But the weight a link carries could vary based on number of links/Outlinks on the page.

thank you yoogi, I discovered another world.
Then you are saying that backlink numer 3 could me more powerful of backlink numer one because the page of the backlink number 3 could have less links. Right?

May I ask you how to search backlinks of one website without displaying pages of the site?

Example:
I type
linkdomain:www.sitedomain.com
but I don't want to see pages coming from www.sitedomain.com

serenoo, Yes. One also should remember that a link from relavant content page would influence search results greatly.

I dont think you can eliminate same domain from search results (not sure), but you can set to see 100 results at a time (options / prefernces) so that you save some time clikcing between pages.