In order to throw someone, you must start by fighting for a dominant grip that allows you to control your opponent’s weight in the direction of the throw. Judo might be among the most specialized martial arts for learning this skill, which is fundamental to practically every technique. Being able to get dominant grips is an invaluable skill that will enhance any martial, and although no-gi is usually touted as more “street practical,” learning this skill with a gi (and learning how to defend against it) provides a precise foundation. Getting grips is often tricky for students who are new to grappling, and it can be hard to focus on securing them at first with so much other stuff to learn. Unfortunately, this is a tricky thing to practice on your own between classes.
But if you happen to have one of those foam pool noodles and an old gi jacket around, you can easily make your own training dummy. Run the noodle through the sleeves and wrap the jacket around a heavy bag, then tie a belt around the collar area to make the arms spring forward a bit. Tie another belt at the usual height, and you can practice setting up grips and light uchikomi whenever the urge strikes.