It is advisable to wear them at all times on the golf course. You also have to protect the rest of you from the sun: slap on sunscreen liberally when you step out onto the golf course, especially your face and arms. Team the glasses with a hat to make sure your face is protected, and you are all set to meet the sun.
Now that we have dealt with the sun, let us move on to the earth. Eighteen holes on the green mean quite a bit of walking. It should be comfortable for you and not damage the turf, or the golf green will not stay green. A pair of golf shoes can tackle this. Golf shoes are designed for maximum ease of movement on grass without damaging the green. Of course, you can wear your regular shoes, as well, but golf shoes are only as expensive as a regular pair of shoes. If you plan on golfing at least once a week, you might as well do so in comfort and be kind to the turf, which can take quite a beating otherwise. If you do not plan on golfing that often, your regular shoes will be enough, but they have to be comfortable. Remember that a pinch on your little toe can affect your drive more than you expect.
As for the rest of your outfit, well, take a peek at what everybody else is wearing. They are likely to know what they are doing. Golfers will always wear what is comfortable, so you cannot go wrong if you take the lead of an avid golfer. A golfer has to walk for a few hours. The key word is comfort. Remember, you want to have a good free swing so formal clothes are not a good option. This is especially important with trousers. Make sure you wear something that you are very comfortable in. Formal pants can give you a rash that will make any kind of walking rather uncomfortable, let alone golfing. What you are wearing should not hamper your mobility.
The most important part is that you should be comfortable in the outfit all day and enjoy yourself. It is worth the time and the effort. Happy golfing!
