It is time to think about colours, for our new gardener I think a simple hot or cool mix is probably the easiest.
Using a designers colour wheel you can create a theme.
Hot mix

A hot mix creates a vibrant planter combine 2 or 3 colours or use shades of the same colour.
Cool mix

A cool mix creates a cool calming or reflective mood, combine 2 or 3 colours or use shades of the same colour.