Squares: Tool Control Bar can give you rounded edges.

Circles: Tool Control Bar can give you partial circles.

If you mess something up, you have infinite undo (Ctrl-Z)! You can re-do as well (Ctrl-Shift-Z).

There is a button on the right of the Tool Control Bar to determine if stretching an object changes line thickness or not.Objects have an order of what is on top of what, and you can change that using buttons in the Selection Tool Control Bar.Click objects again to be able to rotate and skew them.Hold the Control key to keep aspect ratio. Or move your selection using the arrow keys.Control-drag only moves in one direction. Copy-paste and duplicate work as you might expect.Click and drag to select objects in a box.click while holding down Shift) to add an object to the selection. Make sure you are using the 'Select and transform objects' tool (on the top).Ctrl-arrows move your view of the document around.Zoom in and out using Control and scroll wheel.View menu has lots of options for zooming.The magnifying glass enables zooming with a click or a rectangle selection.It changes depending on what tool is being used. You can read more here, but just remember the location of the Tool Control Bar. If it doesn't, then perhaps it makes EPS or PDF files, which can be imported by Inkscape. It is a vector format, which means you don't lose resolution when you zoom in, in contrast to bitmap (a.k.a.SVG is a file format you can open in modern browsers.Here are some essentials, which go along with the following video introduction: There is a lot of great Inkscape documentation out there, and the Basic Tutorial is a good place to start. Inkscape is a cross-platform graphical editor for Scalable Vector Graphics (SVG) files.

Making beautiful scientific graphics using Inkscape

Inkscape vector