1. Change the default title. Bivariate of Height by Weight is a terrible title compared to Kids in Mr Smith's Class.
2. Fix or remove the axis variable names. Date is a terrible title for an axis labeled 1Jan2000 ... 1Dec2000.
3. Remove the busy tick marks if they are not adding anything but noise. Maybe leave out the grid lines too.
4. Play with the legend position. Think about rearranging the legend order. Choose colors to help interpret the data.
The graphics art folks say 600 DPI for a publication that may present the graph as 2 inches by 3 inches. That means 1200x1800 pixels. You might have a screen that big, but you'll need to make the fonts big. (Graph Builder has a fit-to-window option you can turn off to make bigger-than-screen graphs.) If SVG is a choice with the publisher, it might work well--but you might want to test first, there is a bit of leeway in the way SVG is rendered.
Craige