Some call it your prime years, others will dictate a mid-life crisis. Regardless, by this point in your life your style should have done a complete 360 from your 20s and you should notice a significant change from that of your 30s, if not then that's another discussion for another time. For some, your figure is expanding which only suggest more maturity and intelligence in your wardrobe; even if your figure is still intact, simple dignity and class dictates a change in emphasis. Think smart and pick stylish clothes as opposed to trendy ones - there is a big difference between stylish and trendy, and simply buying the same clothes in larger sizes wont cut it. Think in terms of the future, putting quality material and classic shapes at top priority. "Will I still be able to wear this in 10 years?" is a good question to ask when contemplating. Going bespoke is the perfect way to introduce shape into your suits at this point, especially if your a bit wider in the mid-section. If you have yet to start wearing brogues...what the hell are you waiting for? They are a must, especially if you are still wearing jeans(which is perfectly acceptable, situation dictating of course).
Accessories should only be top-notch at this point. Leather is your best friends, with canvas coming in close second. Try for a leather briefcase for work, leather or canvas for travel, and classic sunglasses like wayfarers. Watches are to a man like...watches are to a woman(sorry, couldn't think of an equivalent), so you should have at least a couple decent ones by know. And stay far away from leisurely attire, like trainers and sweatsuits, in public. We don't need another Bush incident - here.