BOOTS. Three main types according to their flexibility.
4 season - for winter and rough terrain - very stiff, can take crampons, have a pronounced heel breast, high ankle cuffs.
2 season/rambling - very flexible, perhaps with no heel breast. Good for low-level tracks and paths.
3 to 4 season - probably the most popular, suitable for most conditions most of the time.

COMFY TOGS. The ideal way to keep comfortable is to use a flexible system of layered clothing.
Base Layer. The best material to wear next to the skin is one that will "wick" sweat away from the body, keeping you warm and dry. e.g. Dryflo. Avoid pure cotton. It soaks up sweat, but won't let it go. For trousers, polycotton, fleece,cord, tracksuit materials are suitable but not denim. Never. When wet it becomes heavy and very, very cold.
Mid Layer. Worn on top of the base layer to provide insulation and should also "wick" or it will become damp from sweat, and its insulating properties will be reduced. These are usually fleeces, thick, thin or a combination of both.

WATERPROOF TOGS.
Outer Layer. The Scottish weather is predictably unpredictable. Your waterproof jacket and overtrousers are your very best friends. Never leave home without them, even in summer. Most effective if made from breathable materials e.g. Goretex. There is a bewildering array of these on the market, but they all work in the same way - they let water vapour escape, but don't let raindrops in. Non-breathable materials like nylon allow condensation to build up inside, creating your own private pool. This can result in you becoming very cold, not to mention miserable.
If you intend to be out in all weathers your jacket should have a stiffened hood visor to protect your face.
Waterproofs also come in a bewildering array of prices. It pays to shop around.

SMALLS TOGS.
Hats. A massive 30% of your body heat can be lost through your head so a hat is a must. Waterproof/windproof versions are available, and also balaclavas. Fleece headbands are useful if you just need to keep your ears warm.
Gloves. Materials as for hats. Some people like to wear thin glove liners with a thick/waterproof glove on top.
Socks. Thick/thin, short/long, wool/synthetic and yes, wicking. You may have to experiment to find out what suits your feet best.
[Small items have a habit of being whipped out of your hand in high winds and disappearing over the horizon, so it's a good idea to carry spares.] This may seem like a lot of fuss, but the appropriate clothing can mean the difference between an enjoyable day out or a battle with hypothermia.

RUCKSACKS. You should be able to meet your needs in the 25 to 35 litre range. As different makes vary in style try a few on. A rucksack that's too small will be an endless source of frustration. There are adjustable versions as well as those designed for women. A waterproof liner is useful.

FOOD AND DRINK. How much grub? This is a matter of trial and error as everyone's energy needs are different. Take more than you think you will need . You will obviously require more calories for a seven-hour walk than a four-hour walk. Avoid things that will freeze in the winter such as Mars Bars unless you want to lose a few teeth.
A hot drink -A glass flask is inexpensive but if it gets broken that's your hot drink gone for the day. Stainless steel flasks are very popular. They are more expensive but they will last forever. Well, a long time anyway.
A cold drink - it is vital to carry plenty of liquid, especially in summer, to replace fluid lost through exertion. Two litres minimum in hot weather. Again, too much is better than running short. Dehydration is not pleasant.

THOSE LITTLE EXTRAS.
Gaiters: Keep the peat hag off your trousers, and stones, heather burrs and small mammals out of your boots.
Sit mat: Something to insulate you from the ground when you're having your lunch. You can buy special mats or a piece of camping roll is fine.
Walking poles: These can greatly reduce the load on your knees, especially going downhill. Even big hunky men use them these days.
Emergency whistle and survival bag: Just in case. But learn what to do with them.
Map and compass: only useful if you actually know how to use them!!
A change of clothes left in your car is A GOOD IDEA.
Basic first aid kit: include insect repellent and don't forget sunscreen, even in the winter.

If you need more information , please feel free to ask. Happy Walking.