A large part of human brain is devoted to image processing. So it should not be a big surprise that many (human) scientists mostly look at Figures and captions. When designing figures for a paper, the goal is to produce something that is so compelling that the reader can grasp the main points of the paper without even reading a single word. Also, figures should be aesthetically pleasing and have style.

Stage 1: Plan each figure panel

Determine the communicative goal

The main function of each figure panel is to communicated a point (or multiple points) between the writer and the reader. When readers look at a well-designed figure panel, they immediately understand what the point is - without having to read the caption or paper. These points can help us to get close to this level of clarity.

To achieve this, you need to be very clear for yourself which points you want to convey with each panel. If you, as the figure-maker cannot verbalize the goal of your figure, then your figures are doomed to be messy, and convoluted. Note that you cannot drive home all the points in your paper in one single graph. Sometimes less is more. Do not occlude data with data.

Sort the points

Each of your desired points can be conveyed with a visual contrast (chance in color, shape, or location of ink). Some of the visual contrasts are easier to perceive so pay attention to how you choose the association. Space > color > shape

Minimalism

It does not matter if you are looking at a machine, a short story, or a scientific figure. In any system, when you know every part has a role, and there is no redundancy, it gives a special kind of satisfaction. You appreciate the design, and the thoughtfull designer. So make sure, you use the minimum amount of ink. Do not use unnecassary ink in your plot unless there is an essential role for it to play. With each line in the graph, ask the question of whether it conveys any information. If not, delete it - the figure will likely look better without. Typical examples include: Boxes around graph panels, boxes around legends, and grid-lines are typical graph-junk that should be removed.

Stage 2: Fine tune and assemble graphs into good-looking figures

Once you figure out the critical points and have decided which figure panels you need to tell your story, it is time to bring the figures to something that is publication worthy. There is a big difference between a good-enough figure, and one that impresses with elegance and style. These step can help you make your figures look not only professional but aesthetically pleasing to look at.

Assemble figure panels into figure and scale to journal size

For the final assembly of a figure, use a vector-based graphics program. Affinity Designer, Illustrator, Inkspace, are good choices. Power point is not. For each figure then decide how wide your figure should be in the final pdf document of your paper and make a document of the correct size. For journal papers, common width are: * 1 column: 8.5cm * 1.5 columns: 11.6cm * 2 columns: 17.6 cm

Then try to arrange your panels to fit the width. Ensure that you have a adequate spacing of the panels without too much space between them. Once you have done this with all Figures, you need to ensure that the formatting is consistent across all figure panels and figures.

Stroke width should be harmonious - at journal size, I recommend 0.75pt for figure axes, and 1-2pt for lines indicating data
Use one single font across all figures (A good sans-serif font as Arial or Myriad Pro is a good choice). Don’t mix different fonts, unless you have a special communicative goal to do so.
At journal size, no font should be smaller than 6pt
As a general advice, the following font sizes look good:
- Subpanel letter (a,b,): 18-25
- Figure titles: 10-12pt
- Axis Main Label: 9-11pt
- Tick labels: 7-9pt
- Legend entrees 8-10pt