When it comes to the jacket, make sure that it hugs your shoulders, is slim in the body and that it covers your bottom.
The trousers should be slim, not skinny, and have a break that suits your personal taste – I tend to go for a slight break so that I can show a bit of sock when walking or sitting down.
Notch lapels are more business appropriate whilst a peak lapel communicates elegance and power. Number of buttons and vents is your prerogative.
For your first suit, go for something in a solid navy or grey and then expand from there – burgundy, olive, khaki and French blue are all viable options. Black is NEVER suitable for business or the day time (if you want something similar, go for charcoal grey instead), but can look very modern and stylish when worn in the evening.
As long as the suit fits you properly, you can dress it up or down to your tastes. Think dress shirts, grenadine ties and Derby shoes or neutral t-shirts, trainers and chambray shirts.