Some good practices when it comes to charts and data visualizations: use high contrast colors, avoid problematic pairings (red-green, blue-yellow), use symbols as well as colors...

Four versions of the same chart. They're showing the monthly rainfall in inches and comparing tropical vs arid during the different months of the year. The first version has low contrast and it is difficult to read. The second one has higher contrast, so it will be easier to read by most. This is especially important if the Increase Contrast setting in iOS is on. But still, it is red for tropical and green for arid. Green-red is a problematic paring of colors and some users could perceive those colors very similarly, making it very difficult to differentiate which line in the graph is for tropical and which for arid. The third graph tries to simulate this perception, where both colors look yellow-ish to the user. The fourth chart uses green for tropical and blue for arid, but it also adds shapes along the line for specific months. It is much easier for everyone to differentiate both lines. Using shapes is especially important if the user has the Differentiate Without Color setting on.