Now that you've cuckolded your husband, your job as mistress is only beginning. From now on you have full control and you'll need to use it. Your husband will need a strong hand to guide him. You'll be telling him what to wear, what to eat, and how to spend him time and his money. His only purpose will be to serve to you. Here are some ideas on how to keep up the dominance.
Semen
On the surface your husband's semen can seem like an annoyance. It's messy, it tastes bad, and it stains linens. But actually it is a great tool for dominating him. The most common way to use it is to force him to eat it. Normally after a man ejaculates he wants to just relax and not think. He wants nothing to do with sex for a while. So having him deal with his cum after an orgasm is something unnatural to him. He absolutely won't want to do it. Therefore it will require a command from you and an act of submission from him - great practice for more advanced cuckolding. This is great training since he will be doing many more "unnatural" things later.
Do this by making the rule, "From now, on every time you cum, you have to eat your semen." If you let him jackoff, make him lick it up. If he's wearing a condom, pour its contents into his mouth. If he cums in your pussy, make him eat a creampie. You can get creative too, like making him cum in a glass then drink it at dinner. Or save each one of his cums in the freezer to eventually make a cumsicle for him.
He doesn't have to necessarily eat it either. If you really feel like humiliating him, you can make him cum all over his face and then not let him wash for a while. As his semen slowly dries on his face, he'll become uncomfortable and wish he had never cum.
Another related rule to make is that you no longer want his cum touching you. Say, "It's dirty". The contrast of him eating and wearing his own cum while you refuse to even touch it will speak volumes. You're obviously too good for his lowly seed.
His Penis
Another seeming headache for you will be you husband's penis. It's small, it cums too fast, and it doesn't give you pleasure. If you're smart though, it can be a useful tool in humiliating him.
Feel free to openly make fun of his penis. Call it demeaning nicknames like "Dicklette," or "Pee-pee." Don't call him by his real name either, refer to him by his penis, like, "Come here, Tiny". Let him know constantly that you think his cock is inadequate. Contrast this to praising your dildo. Let him be in the room with you as you masturbate with it. Let him know how good it feels to be fucked by a "real cock." Make sure to cum real hard on it. After you're finished pleasuring yourself, show him you used and pussy and tell him, "This is what my pussy looks like after a real cock has been in it." Then make him lick the dildo clean and to treat it like a holy object.