There is no need to buy specialist angling clothing unless you want to ‘look the part’.
It is best to avoid bright colours as you do not want to be any more visible to the fish than you can, but apart from that any outdoor clothing will be suitable.
You will be outside and not moving around a great deal for quite long periods, so make sure that you have sufficient clothing to be warm, and to keep dry if it rains.
In winter, it is best to wear several layers of thin clothing to trap warm air, rather than a single layer of thick clothing.
Take care also to ensure that there are no gaps, such as a shirt pulling out of your trousers, as this will create ‘cold spots’ that are uncomfortable and can result in a lowering of body temperature.
A hat is recommended, both for warmth in winter, and so that the peak of a cap, or brim of a hat can shade your eyes from the sun in summer.
Waterproof boots or shoes are also advisable, and in winter it is a good idea to wear an additional pair of thick socks as your feet can become very cold if you are sitting still for long periods of time.