If you want to get more comfortable at being upside down, the wall walk might be your new best friend. All you need to do a wall walk is some open space and a wall.
The wall walk is a skill that has multiple benefits for your body. Not only will it help you develop strength for handstand holds and push ups, but it also builds strength in your arms, back, core, shoulders, and wrists.
Start by lying in the floor in a prone position with your feet touching the wall and your head facing away from it. Extend your arms and place your feet firmly on the wall.
While maintaining a neutral spine, begin to climb your feet up the wall. At the same time that your feet ascend the wall, your hands will move closer to the wall as well.
Continue all the way up until your thighs and chest come in contact with the wall. At this point, you will essentially be in a handstand position with the front of your body in contact with the wall.
From the top position, begin to walk your hands away from the wall as your feet climb back down. Try to complete this with as much control as possible. Return to the prone position on the floor. This is one rep.
If you're just learning how to do wall walks, start with walking as high up the wall as you feel comfortable and safe doing. As you get more familiar with the positioning and strength needed, you can start to go higher.
It is also necessary to keep your arms extended throughout the entirety of this movement. Think about keeping the glutes and core engaged as well.