We went to Scotland for a two weeks hike, and this is how we did it:

2. Went through our camping gear to see if something requires repair/ replacement. There's two of us, so the basic equipment is a small tent, 2 thermomats, 2 sleeping bags, camping gas + ligher, 2 0,6 litre aluminium mugs, 2 spoons, 2 knives and 2 flashlights. With this you've got sleeping and eating covered.

3. Stocked on food; you don't really need to do this, but that's our way of saving money and being more independent. 

4. Packed the usual set: 1 pair of boots, 1 pair of flip-flops, 1 pair of shorts, 1 pair of military trousers, 2 fleece shirts (one light, one warm), 1 waterproof jacket, 1 pair of waterproof trousers, 5 pairs of socks, 5 pairs of underwear, pyjamas (cotton shorts+ tshirt), 4 tank tops. Plus some common meds, cosmetics in small containers and small versions of items one uses on a dali basis (hair brush, tooth brush, etc.), tissues, sunglasses, a notepad and a pen, some general maps & info printouts (we bought more detailed ones when we got there), cell phone + charger, a compass. 

5. Kept our backpacks under 15 kg (most of it was food). 

6. Planned the route: we defined the area which we wanted to cover, checked points of interests and possible accommodation along the way, figured out the alternative options. We decided on The West Highland Way and it's surroundings + Isle of Skye.

7. Went.

8. Had a great time. 

Basically, for us it was a regular trekking trip gone international and a dream come true- I'd wanted to visit Scotland since forever.