Sketchbooks can use normal paper, cartridge paper, or watercolor paper.
What is cartridge paper? This is a high quality type of paper used for illustration and drawing. They differ by weight and can be smooth or mildly textured (sometimes called fine or medium grain). They are wonderful to draw on with pen or pencil.
Different paper are suited for different uses because of its paper weight and its surface treatment. For normal and cartridge paper for example, they are good for pencil and light ink work, but aren't suitable for using any wet mediums. Watercolor paper is treated with a coating so that the paint doesn't bleed or seep into the paper. The coating also makes watercolor pigment look more vibrant.
For watercolor paper, it's important to note the cotton content. The higher the cotton content, the more durable the paper. 100% cotton are tough and can be used for multiple washes. For lousy wood-based paper, you can see paper fiber coming out when you put on too many layers of washes. 100% cotton paper is expensive, but worth the money. Some paper would have a mixture of cotton and wood-based paper to bring down the cost. You can use watercolor paper for colored pencil. I find that a mixed media journal works best for our lesson, because we use so many different medias, I find it holds up best.
Journal paper also differ by the texture on their surface. Some are smooth, some mildly textured and some rough. The smooth and mildly textured paper are good for pencil and pen. The textured and rough paper are good for watercolor.
I learned all this just by trial and error and for the most part, you will find the type of journal that works best for you and the mediums you like to work in most.
INSPIRATION can be found in every situation, be it a positive or a negative one. However, there is no true INSPIRATION that can be compared to the one only found in the hope of Jesus Christ our Savior.
Look around allow yourself to be INSPIRED!