Lincoln gets a call from Clyde at one o'clock in the morning with some news. After overhearing his dads having a conversation, he believes that they are going to have another baby, and asks for advice on how to be a great big brother. The next morning, Lincoln tells him the three C's on being a great big brother: Confidence, Caring, and Cookies.
With fanny packs full of snickerdoodle cookies, Lincoln begins training Clyde by showing how he cares for his younger sisters while Clyde is taking notes. Lincoln starts off with helping Lily after she injures her thumb. Next, he hears the twins arguing and enters their room. Lola wanted Lana to guard her castle, but she thought it was boring and attacked it instead. Lincoln resolves this conflict by pretending to be a troll. In the kitchen, Lincoln gets a bag of frozen peas from the freezer after hurting his eye from the twins and makes Lisa some PB&J sandwiches. He then gives Lucy rhyming words for "tomb". Feeling confident that he knows what to do, Clyde decides to fill in for Lincoln when he hears Lana and Lisa arguing upstairs. However, at the same time, Lucy tries asking advice on how he knows when he's found a soul mate, and then Lola comes to him asking to choreograph her ribbon performance. Lily then comes to him with a broken toy. Feeling overwhelmed, he throws them the whole fanny pack of cookies and tries to leave the house, only to find Lori at the front door and passes out.
Upon waking up in Lincoln's room, Clyde feels that he doesn't have confidence like Lincoln and gives up on learning to be a big brother. After Lincoln leaves the room, Clyde starts playing video games until Lisa comes in asking for him to tie her shoes. After that, she calls him a lifesaver and leaves. Lucy suddenly appears in the room and asks Clyde for words that rhyme with Lori. After giving her thousands of words, she thanks him, calls him a lifesaver and leaves. Lola then rolls in with her car and asks Clyde to show her how to buckle her seat belt. Once he gives her proper instructions and her seat belt is buckled, she also calls him a lifesaver and drives away. Lily crawls to him with a book and he reads her a story. Feeling more confident, he heads downstairs to search for Lincoln, only to catch him by staging the whole thing just to boost his confidence. Angered by this, Clyde hands him Lily and is about to leave until Lana calls out to him while stuck in a tree. At first, he believes it's also part of the act, but Lana tells him she's actually stuck and that she and her rat, Bitey are afraid of heights. Clyde then retrieves a ladder to get her down and once they are safely back down, she calls him a lifesaver and runs off.
Lincoln finds him and tries to apologize, but Clyde reassures him that he is feeling confident enough and is going to tell his dads he is ready to be a big brother. However, later that evening during dinner, Clyde's dads tell him there's been a mix-up, and that they've adopted a new kitten from the animal shelter. The next day, when Clyde is about to be left home alone with the cats, he tells his dads he's got the three C's down, only this time the third C is cat treats.
Lincoln and Clyde are shown as babies on the title card. Lincoln's tooth is not chipped, implying that he had chipped it later in his life. Clyde is wearing his glasses, implying that he has needed them since he was a baby.
It is revealed that Lana is afraid of heights and so is her rat Bitey.
Lucy's notebook has the initial L.L.L., meaning that her middle name may start with an "L".
When Clyde panics over fear of messing up Lola's ribbon dance choreography, he fears she will start holding up convenience stores, which is a callback to "Butterfly Effect" when she did it along with Lynn.
It is revealed that Lily knows how to say the word "cookie".
The first part of this episode is skipped when it aired in Nickelodeon Philippines.
Also, the last part of this episode was cut.
In the Italian dub of the episode, cookies are replaced with crackers.
This change was probably done because they look more like crackers than cookies.
It was also to keep the three Cs ("Confidenza, Cura e Cracker").
In the Latin American dub of the episode, snickerdoodles are replaced with chocolate chips cookies.
This change was done because of the three Cs adaptation ("galletas con Chispas").
Baby Steps - The title of this episode means to make progress on something in small increments.
Mickey Mouse - When Lincoln opens his drawer to get his walkie-talkie, one of the toys he has resembles the famous cartoon character.
The Simpsons - When Clyde is giving Lucy ideas for words that rhyme with Lori, and he gives her "glory", "story", and "Montessori", these are the same words used in the episode Brother From the Same Planet, where Lisa calls the Cory Hotline, and she is given the same words for words that rhyme with the name Cory.
In the scene where Lincoln hands Lily a cookie, she has visible eyebrows, which she normally doesn't have.
With only one tooth Lily can't bite a cookie.
When Lincoln says "Six year-olds can spell!" while Lana and Lola are attacking him for the cookies, Lincoln's teeth are shown, but his chipped tooth is missing.
Lincoln made Lisa four peanut butter and jelly sandwiches shaped in triangles with the crusts cut off. But there are three of them.
Lola is shown with a full set of teeth, when Lincoln tried holding her back against Lana.
In that same scene, Lola's eyelashes are disconnected, while Lana's eyelashes are missing.
In Lana and Lola's fight dust cloud, one of Lucy's legs is seen popping out from it despite the fact she wasn't there.
Also, when Cleopawtra and Nepurrtiti were attacking Clyde for cat treats at the end of the episode, Lola's tiara is seen popping out from it despite the fact she wasn't there.
Clyde is seen throwing his fanny pack of cookies to Lincoln's younger sisters, but in the scene where Clyde starts to run off, the fanny pack is back on him.
When Lincoln was talking for the first time with Lisa, in the fridge there were only two notes, but later when he was talking with Lucy, there were a lots of notes.
In the Swedish dub, when Lincoln says "Love that enthusiasm, Night Owl, but it's 1:00 AM", he speaks in Lana's voice.
In the Dutch dub, Euros are the used currency despite other episodes using dollars and the setting being specified as being in the USA.
In the scene where Lincoln says "Okay, Clyde, allow me to introduce...", his tongue is missing.