When the weather turns colder, every man needs a great jacket or coat to turn to. From duffle coats and parka jackets to a classic mac or gilet, there's a perfect jacket or coat for every occasion. Here Mr D reveals how to keep warm and look cool.

A great jacket or coat is often an expensive item, which means men don't buy a new one as often as we might. But we really should. There's a huge array of styles, cuts and colours to choose from, so mixing up your collection can really shift your look without too much effort. Plus with each new season, menswear fashion and trends move on, more than you'd expect, offering the sartorial man something new to keep him interested.

Styles of jackets and coats

So, first things first - know your styles and what's going to work for you and your body shape. Key looks right now are the military-style jackets - those with quite a structured fit, prominent pockets and piped detailing. They may be military green or khaki too, but the look is more about the style than the colour. Also look out for brightly-coloured cagoules. These lightweight waterproofs are designed to be worn over several layers and offer a playful, vivid look. Other timeless and classic styles to look out for include:

1. Parka jackets - these three-quarter length jackets (to the thigh) are distinguished by the often-furred hood, man-made fibres and their effortlessly casual look;
2. Duffle coats - frequently made of a heavy-wearing wool, again three-quarter length with distinctive toggle fastenings;
3. Overcoat - the ultimate classic cut jacket, made of wool or Scottish tweed, designed to be worn over a business suit and on, or just, beyond knee-length;
4. Mac - lightweight man-made fibre jacket, often incorporating a waistline-belt and cinches on the cuffs; and
5. Gilet - also known as a body-warmer, these jackets are sleeveless, are usually feather-filled and distinctive by their slightly bulky appearance.

Aside from these, there are the ski-jacket style or biker-esque leather jackets. Having a range can help set the tone for your look. For a smarter setting, try a mac or overcoat. In a rural setting, the gilet or wax-jacket style which British brand Barbour is famous for. For the biker look, Belstaff is excellent.

Fabrics for jackets and coats

The key distinction between fabrics is whether they're made of natural fibres, such as wool or cotton, or man-made fibres, such as polyester or other high-performance waterproof materials, such as Gore-Tex. For most other clothing, I would always recommend natural fibres, which are more breathable and provide a more comfortable fit. So a great jumper is always made of high-grade wool, like merino wool, or cashmere.

However, a great jacket or coat offers the benefits of being waterproof and windproof, keeping you warm and dry. Man-made fabrics are much better at doing that. They can also be lighter-weight, which is useful when travelling, or undertaking adventurous sports.

Colours, cuts and sizes

• There are no hard and fast colour rules here, but autumnal/wintry colours can often work best - so the classic colours of blacks, greys and blues match well and can look quite smart. Rustic browns and olive greens suggest earthiness and are a little more relaxed. Beiges make an interesting change while for something completely different, psychedelic block colours can be quite startling.
• As for cuts, generally the longer the jacket, the smarter the appearance. Also, the more fitted, the more business-like your look. Fewer pockets, absent hoods and reduced detailing (so no tassels or ties) will suggest a sharper look. But often the intrigue is in the detail, so feel free to experiment.
• Remember with sizing that you'll need something larger than normal - you'll often be wearing layers so be sure to try the coat on with plenty of your usual clothing on underneath.

So when things take a turn for the cooler, do I mind? Not at all - I'll take any excuse to break into my collection of jackets!