A few years ago heathenX and Richard Querin created a series of tutorial videos for Inkscape, a Free and Open Source vector graphics program that can be downloaded from http://inkscape.org
The original heathenX website no longer exists, however I have obtained a backup of all their tutorial videos and will be uploading them to Youtube over the coming months. All the videos are licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) license
(https://creativecommons.org/licenses/.... You are welcome to share and modify them in any way, but if you do so they must remain
under the same license, and must be attributed to Richard Querin and heathenX.
If you are the sort of person who prefers lengthy, written tutorials, rather than a Youtube video, my own series of Inkscape tutorials for Full Circle Magazine can be downloaded for free from https://fullcirclemagazine.org/inksca...
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NOTES: The layout of the Fill and Stroke dialog has changed in recent versions. The three marker dropdowns are now in a single line, but they still select the start, mid and end marker, in that order.
The issue with markers you've created appearing as a coloured square, rather than a representation of your marker shape, is still present in recent versions of Inkscape.
There appears to be a bug in recent versions of Inkscape that results in markers being drawn at the wrong size. I don't know of a workaround short of going in and manipulating the SVG file by hand.