multiple domains - how does one best do it?

[LoveNotWar]

I am sure that this has been asked before, but I cant find a satisfactory answer ... so perhaps someone can give me a simple, laymans perspective!

We have www.boatbookings.com (already propagated and pointing to our hosting space) and also www.boatbookings.co.uk ... should we point this one to the exact same space using the same nameservers and so on ... so that whichever one someone clicks they find themselves at the same website ... and as an extension to that if we get any other domains (we are considering buying similar domains just so that we have them) do we do the same? Or is there some other way of doing it ... do we have to have a hosting package set up for each and use permanent 301 redirects or what? I ask this both from a technical and Search Engine optimisation standpoint. If we do it wrong I believe that we are likely to be penalised.

[cyanide]

Any domains that you want to point to an existing domain can be simply accomplished through your domain registrar. Most have some kind of domain forwarder.

[Brand Digital]

Yes, you can certainly point a domain to another through your registrar, but what is the best way to increase rankings for the primary site?

For example, I have a client with a primary site and several additional domains that pertain to areas within the site other than the homepage. Should we point the keyword rich domain to the sub-directory with the relevant content or push the relevant content out to the keyword rich domain?

If we re-direct, should we actually host the domain and install a 301 re-direct or just have the registrar direct traffic to the primary site?

Thanks

[cyanide]

Pointing domains to another won't help its rank.

If you start advertising and bringing in links for all those domains that point to one website, you're just going to be raising red flags for Google.

Should we point the keyword rich domain to the sub-directory with the relevant content or push the relevant content out to the keyword rich domain?

Pointing domains to sub-directories just for the sake of SEO will most likely have a reverse effect.
Not necessarily being banned, but certainly have a lessar weight in the eyes of google