Balsamiq Mockups is a great digital tool for sketchy looking, low-fidelity wireframes. You can focus on your vision, and priorities, without being lost in the details of the layout, contents, images, navigation, or technical possibilities. It's probably the closest digital approximation to hand-drawn sketchy wireframes--the ones you make during a meeting or on a napkin in a pub.
Most common UI elements can be found in the UI library on the top of the screen. If you can't see the stripe with UI elements, you need to open it, by clicking on the Show UI Library button ( 
). Alternatively, you can press Ctrl + ...
