What kind of essential baby items should I include on my registery? First time mom & not sure what to get.?

Im 18 weeks pregnant & on Tues I have the gender ultrasound to hopefully see what the baby is. I plan on registering after the appointment with my mom & fiance & Im unsure about what eseential baby items to make sure to include on the registery. This is our first child & I thought my mom could help us, but Im 29 yrs old & she says it's been forever since she had kids & she doesnt even know about stuff like a diaper genie lol. Any help is appreciated!!