Lines are much more complicated and rewarding than most people give them credit for. In fact, many professional interior designers create mood and motion in interiors through lines. This is because the varying types of lines can evoke emotions, give the illusion of action, and can also improve flaws in design.
Horizontal Lines
Horizontal lines, like any line, can be used anywhere but they instill a restful feeling in us, as they remind us of laying down. Therefore, a very effective place to put horizontal lines would be bedrooms and places of rest and relaxation. They also make small rooms look wider if used on an accent wall.
Vertical Lines
Vertical lines, if they have high contrast, can make viewers feel alert, but less contrast can eliminate that affect. They also feel sturdy and strong, but too many of them can remind us of a jail. They also make walls seem taller.
Diagonal Lines
Diagonal lines are typically stronger in terms of effects on the viewer than horizontal and vertical. They represent motion, but too much can make us feel unsteady.
I do not recommend not mixing stripes and/or using strips that are too small, too large, all enclosing, or (for lack of a better word) adolescent.
