I want to improve my pagerank for a belgian website (.be). Is it better to buy/trade links on .com's or only .be's? Any ideas on this one?
any domain extension will do, but if .com are still available I'll go for it since people usually type .com first before entering another ext.
If you specifically want to raise your profile for Belgian searchers, then, yes, my understanding is that links with Belgian sites, and sites with a Belgian tld, are the way to do it.
I don't understand. It's much more difficult to improve a .com's pr. So why would I do that if I only want to improve my ranking on search engines in belgium?
If you're geo-targeting certain keywords, it would be best to get more localized links. However it's more important to get links from sites ranked well in that region, regardless of their domain extension. You can check Geo SEO to target what sites would be best per country etc..
Since You have a .be domain, You should also get hosting in Belgium. This will help You rank better in google.be.
This is quite a useful tool to check how you are going as well: http://ekstreme.com/domain-geolocation/ It applies some of the techniques from above - but doesn't really have the same complexity. Dylan