For graphics and diagrams, I use vector images.
Use Microsoft Word (or LaTeX editor), not Google Docs.
You can export SVGs for Word from Adobe Illustrator.
You can export vector images for Word from PowerPoint, or it's the same from excel too.
Saving your final PDF from Word for submission.
Flourish.app: Graph making software that lets you export to SVG on their free plan.
LinkedIn Leaning: Very well done training videos for learning software for free through DoIT.
Kate Baldwin