This Inkscape extension lets you delete lines shorter than a given threshold. The extension was made to clean up heavy PDFs exported from SketchUp, but can probably be used in various other situations too. *Install* Copy the content in src/ into your Inkscape extension directory. The extension directory path can be found in Edit > Preferences > System inside of Inkscape. Tested in Inkscape 0.91 and 0.92 on Windows 7 and Windows 8
This tutorial helps you understanding lines and nodes in Inkscape. I'm not the best of an artist myself, so I used an image of a crafts tutorial I liked. Here's the link if you want to learn how to draw this nice kitten by hand: https://www.youtube.com/watch?v=qqon8BQTcK0