First are you sure you can actually hold a handstand for three seconds because that is actually quite a while. If not you need to get your body in a straight line directly over your hands and keep your legs straight and together and core tight. You should look at your hands but not by bending your neck right back and sticking your head out. If you can hold a handstand for three seconds you must have a good handstand already so it is more about arm strength because your arms might be starting to give out after three seconds. Practice should help as should arm strength exercises like press ups and straddle hold.
Maintaining balance during a handstand is what makes you stay up but it requires that your hands are strong enough to hold your weight and requires your body to be able to lift itself up and remain in the air
Hold your arms very straight and strong as your down there. If you feel your gunna fall start walkin with your hands thats always helped me! Aww i miss gymnastics :(
Squeeze your muscles really tight. (abs, butt, thighs) It really helps. Also practice really close to a wall to if your about to fall you can use the wall to balance yourself.
I can get into a handstand but I fall after like 3 seconds. Any tips to hold it longer