If I could offer only one piece of advice to any scientist on how to improve the figures and presentations they produce, it would be ‘Learn how to use Inkscape’. If you ended up here by searching for “Inkscape scientists” or some variant of that, then what follows is just confirmation that you’re looking for the right thing.
Inkscape is a cross-platform, open-source vector graphics editor. Let’s break down all those adjectives to see how they help:
Cross-platform: it works on Windows, Linux, and Mac
Open-source: it’s completely free (no sign ups or limited trials)
Vector graphics: text, lines, shapes, colours, curves, (and even images to some extent) remain exactly that. In other words, they’re not flattened to a collection of pixels with a consequent loss of editability (if that’s a word). See know your image file formats for more information.
But what does it do?
Like any useful skill, there is a learning curve to Inkscape. That’s not because it’s hard to use, but because it can do so many things. For example, I use Inkscape to
- Create schematic diagrams from scratch
- Take figures from scientific papers and remove details that I don’t want, so as to produce a simplified figure for a presentation
- Adjust plots exported from other programs such as Matlab, Python, or R
- Add details to photos such as scale bars, arrows, or outlines
- Produce scientific posters
Once I even used Inkscape to create a table because it was too large to create with standard methods in either LaTeX or Word.
Where to start
There are countless tutorials online, so I’m not going to give you my own. Instead, I’ll simply show a screenshot of a real-life example to give you a first impression.
Head on over to inkscape.org, download it, and start experimenting.
Other options
Inkscape is similar to Adobe Illustrator and Corel Draw. Admittedly I’ve used neither, but I get the impression that for a scientist’s purposes, they add nothing other than a price tag. (Graphic designers may feel the need to pay for these programs to adhere to their industry standards, but us scientists don’t need to worry about that).
What not to use
Inkscape is much better suited for editing figure compared to any of the following:
Any Microsoft Office product: sure you can draw lines and shapes in Word or PowerPoint, but that’s about your limit.
Paint: I used this a number of times as an undergrad before learning Inkscape, but thinking back to that makes me cringe.
Photoshop/Gimp: These programs are for editing raster images (photos essentially). Using them to edit scientific figures is like using a knife instead of a saw to cut a tree: you might be able to do it, but there will be much frustration along the way.
Brushing Up Science 
Thank you for the write-up. I am putting up a tutorial on using Inkscape in the sciences. The playlist is here https://www.youtube.com/playlist?list=PLxtauMB7RON_2tg-mRQTuieFUr29IOKzW
I will continue to adapt the tutorials as comments come on my channel. For now I will continue with illustration in the life sciences and chemistry. Later I will do some thing on engineering diagrams.
quite elegantly written and very helpful.
maybe try sharing your tutorial on hackr and quora. https://hackr.io/tutorials/learn-inkscape