Gridwork. I love them because you can put the first jump super low so you don’t have to worry about the height but it puts you on a perfect stride for the rest of the grid. It also means you can practice your position without worrying about finding distances or navigating around a full course!
Start small and easy at a height that you feel confident at. Then go higher and when you feel confident at that height raise the jump again. This way you can reach your height goals at a pace that you want to go. Also if you do pony club or have local shows/events enter in the jumping and this will also boost your confidence.