Scottish singer Paolo Nutini once released a catchy single all about putting on a brand-new pair of shoes in the morning. It may be a banger, but maybe don't take it as literal advice because experts say the afternoon is the best time to try on that new footwear you've been eying.

A healthy back campaign in Germany is calling on consumers to avoid buying shoes at the wrong time of day, as this can have a negative impact on how comfortable the shoes are and, more importantly, lead to back pain, among other problems.

The explanation is pretty straightforward. Your feet change during the course of the day, expanding in length and width throughout. That's why it helps to buy shoes in the afternoon rather than in the morning.

It's also a good idea to wear the same socks you are likely to wear most often with the shoes, just to make sure the fit is right.

A good shoe will promote a natural rolling of the foot and be cushioned at the most heavily used points, such as the heel. The sole, meanwhile, should be more flexible and not made of a hard material, experts say.

If you wear insoles to support splayfoot, fallen arches, or other foot injuries, it is better to take them with you to the fitting. And you should only choose shoes that have a removable insole so that you can replace it with your medical insole.

Speaking of the right fit, when it comes to sizing, foot doctors say you should aim for at least one finger width of space at the toecap. Toes need extra space so they can slide forward when you are walking downhill. It's also important that the heel fits firmly inside the shoe.

If you often get dizzy or light-headed, you should avoid shoes with a very soft sole, as these can only make things worse.