Every sentence must begin with a capital letter and end with a full stop.

Example: Milo rides a bicycle.
Always check what you have written. Every sentence should make sense. Thus the order in which we arrange words in a sentence should make sense. Changing words around changes the meaning of the sentence.
Example: Milo rides a bicycle. A bicycle rides Milo.
Types of Sentences
There are four main types of sentences you can write.
An interrogative (question) sentence ask something.
Example: Is that Milo’s bicycle?
An Imperative sentence gives an order or command or request to someone to do something.
Example: Please, ride carefully.
An Exclamatory sentence shows that the speaker feels strongly about something. It is usually followed by an exclamation.
Example: What a beautiful bike!
A Declarative sentence is a statement that tells us something.
Example: Milo has a bicycle.