Tip #1Wash your hands before and after you play with your slime. Add a bit of unscented lotion to your hands if the slime too sticky to touch.
Tip #2Keep on kneading your slime. The more you play with it, the more it will become firmer and less sticky to touch.
Tip #3If your slime is still sticky, then add a little bit of activator to your slime. You can try a diluted solution of borax (1 or 2 teaspoon of borax to 1 cup of water), or add a few drops eye drops/contact solution to your slime.
Tip #4Add a little bit of unscented lotion to your slime if it gets too hard to stretch.
Always keep your slime in an air tight container, away from direct sunlight so it can lasts longer and stays fresh when you play with it again. I recommend storing it in the fridge.