Good Good
So like you said, Genjutsu is the style of ninja combat that relies on illusions. It can affect either the user or the opponent. We'll discuss breaking Genjutsu later, since that one needs to be clarified more (very important). For now, we're going to move straight onto the actual illusions themselves.
First off, I'm going to break down the categories of Genjutsu. Those are as follows: Paralysis & Restriction | Deceptive | Concealment | Hypnotic
With each category, you'll be asked to group each respective Genjutsu Technique into the correct category. We'll start off with Paralysis & Restriction Genjutsu. While most Genjutsu obviously already deceive your senses, Genjutsu that fall under the Paralysis & Restriction Genjutsu are not as subtle. In fact, they're pretty blatant at what they do. The main sense that is affected is the sense of touch, and it's used to bind the targets' movements or actions.
In these types of Gen, while you may know that you're in a Genjutsu, the part that understands what a genjutsu is, is not what's being effected most of the time. What's generally being fooled is the part of the brain that controls your voluntary motor movements and even involuntary ones, like breathing. However, even in severe cases where one feels as though they are suffocating their body will not simulate such extreme adverse reactions that would literally cause you to cease breathing. So to sum it up, if an illusion is affecting motor movements, it's going to fall under Paralysis and Restriction. The way these generally happen are working tandem with your vision. Common illusions can be roots sprouting from the ground that wrap around your arms and legs; you feel specific tightening pressure around the areas of the arms and legs that were targeted in the genjutsu. Snakes that constrict around your body as if squeezing the life out of you and making it hard for you to breath; you will feel a tight pressure around your entire and your breath may even become shallow as a result, etc.
So say you had an illusion designed to bind your arms and legs with roots int he ground. Regardless of whether you knew they were illusions or not, you would be unable to avoid them in reality since your motor movements would be stunted by the effects of the Genjutsu. Your body wouldn't act as you'd would want it to, so you wouldn't be able to avoid them. Granted, the fact that you would notice your own body failing to follow what you'd want it to do before getting trapped would be a good signal of realizing one was inside a Genjutsu.
With all that said, if you have any questions, feel free to ask. If not, I want you to look through the canon Genjutsu list and post all the Paralysis and Restriction Gens you could find. Also, since this is Gen training, also be sure to post the "tell" for determining you're inside of a Genjutsu.