Greetings George,
First I would like to recommend a must have book to you. Ship Models from Kits, Basic and Advanced Techniques for Small Scales. This book was written by David Griffith. It addresses your question and anything else you may want to know about building small scale ships. I was not paid for this endorsement. 
With respect to your question the author recommends using filters for weathering ships. Basically you apply a clear coat of Future/Klear Then apply diluted turpentine/oil paint in a ratio of about 20:1. Very thin and hardly noticeable. The oils he recommends using are black, white, dark brown (such as burnt umber) and blue such as ultramarine or indigo. The technique is to dip a flat brush into the mixture and wipe most of it onto a paper towel leaving it damp enough so that when you apply it it just dampens the subject piece. Work in vertical strokes since that's how gravity works. If you see too much color just run some more turpentine onto the model to lighten it up. The author suggests black, followed by white, followed by brown, followed by the blue. You do several layers of each color. Depending on the subject you may want to use more.
The author also suggests using a pin wash around details.
The key is to go easy. Don't over do it. The book explains better than I did. I think you'll be very pleased with the results and you'll get the result you're looking for.
Dave