filter advice

I was thinking of trying some colour filters, are they worth investing in?

No, they're not. That is, unless you're shooting B&W film. Photoshop will replicate these and even exceed the quality of even the best colour filters. I would invest in a polariser though.

If you are doing landscapes you my wish to get a set of cokin filters, If you have large size opticals like 77mm size, go with the P series. There is the smaller A series (and less costly) lens diameter may be a problem, and there is a larger series of filters if the P series is to small.

The cokin filter that are a must to have are the graduated neutral density filters.

To see all the filters and samples check out this link: http://www.geocities.com/cokinfiltersystem/theguide.htm