You may also want to change the layer symbols to increase the contrast between them. Select the layer in map tree and then right click the mouse to open the context menu. Select Layer Properties in the context menu.

In the Layer Properties window, click the symbol displayed in the middle.

In the popped-up window, choose the symbol that you want. Click OK to save your settings and close the pop-up window.

Click Apply on the Layer Properties window to apply the symbol to the layer. Then, close the Layer Properties window.