Flowerbeds and Borders: The best way to retain soil is behind a landscaping brick. This will stay sturdy, look clean and crisp. This can also help when you have different levels in your garden and you can then use them as steps to match the beds.
Fencing: There are a few different styles of fencing that is available the most used fence is concrete posts with a concrete base and a wooden panel.
Wooden posts with runners and featherboard is usually used on new builds as they can be easily fitted when the land is on a slope and they are permanently fixed so that they won't go missing.
A selection of beds using brickwork or block. different shapes and heights can be built this way to make different levels of interest. Using a landscaping brick means no need to attach wall caps.
These can be filled with soil, wood chippings or gravel.
Here is a selection of fencing showing different heights. As you can see if you keep the fence level at the top (rather than stepped) then it looks much neater.
This wooden style is Close Board which is the stronger style board.