I want to buy a domain that contains some popular words, and which is occupied by some squatters. The domain is due to expire soon. How should I proceed ? Should I wait until the expiration day, and then buy that domain from a reliable registrar ? Should I somehow pre-order that domain name to the current domain registrar ? Or what ?
There are several options:
1) wait the domain to be dropped and buy it then (if it is really good domain that may be a hard work(check Litso`s answer)
2) if you have legal(law) possession of the word(trade mark, company name etc.) you can claim the registrar to give you the domain control - this can be a slow and painful procedure and I am not sure that every registrar do it
3) you can make regular checks on website that sell expired domains(or ones that will expire soon).
4) there are some really good domains on sale, this is expensive option but depending from the aim it can be really profitable
UPDATE: Check this question How important is the domain name for SEO it may make you reconsider the need of "super" domain
As soon as it's dropped by the one who owns it now it probably goes into quarantine for a while. I believe this is three months, but I'm not sure. This is done to prevent domain squatters from stealing domains the moment in comes free in case the original buyer forgot to renew his subscription.
If it's a really good domain name you can be sure that there's companies out there that do a regular check on that domain and they'll see when it's dropped into quarantine, so that they can register the domain the second it has become really free. If you think the domain is not popular enough for companies to do that you should just check with a normal registrar (GoDaddy or similar) regularly if you can register it. Another option is to contact them personally and ask if you can take it over before it drops from quarantine. There may be a chance that you awaken a sleeping dog though and they'll renew it just to have you pay more.
My bet would be to wait it out and try and register it as soon as you're able to without contacting them, but as I said if it's a really good domain name chances are someone will beat you to it.