April's colour of choice will be navy blue. There isn't much that doesn't go with navy, though personally I wouldn't pair it with brown (unless of course I found a brilliant print that incorporated the two). I would only put navy with black if I had to, but that can't be necessary in April! For spring I always think about yellows and greens, even though neither has a major role in my wardrobe; they make the serious dark blue seem so much more light-hearted.
One of the best pieces of advice about clothes I've come across - and it works for men as well as women - is about contrast. Believe it or not I've had to go away and do some research to figure out the right terms, and I'm still not positive, but I believe it's about value or brightness. The advice is that if you have both fair hair and fair skin, or dark hair and dark skin, you will look best if your clothing is all of a similar brightness, ie all dark shades or all pastels, not a mix.
Taking the other side, now that I have dark auburn hair and even fairer skin thanks to the English weather, I find that wearing dark clothes with light ones works better, eg a white tee under a dark sweater. It's not earth-shattering stuff, it just look more right somehow. For a while I thought the contrast would negate my aim to wear similar colours in order to appear taller and thinner, but then I found this advice on Inside Out Style, one of the most useful style blogs I've ever met.
Best of all, I like the crispness of navy and white together. This also reminds me of Vivien's and my trip to Corbridge last August when she knew I would be wearing white and aimed to coordinate.
Who says you have to be serious after you retire?