しかも

しかも means "what's more", "on top of that": it adds a second fact that pushes the first one further in the same direction. It opens the second sentence, or follows a て-form inside one sentence.

Good news gets better and bad news gets worse. The second fact is often about the same person or thing as the first, and it is the more striking of the two.

しかも or それに

それに adds one more item to a list, often one more reason, and is the conversational choice. しかも makes the added fact stand out, and works in speech and in writing.

Don't mix it up with しかし, "however", which looks alike and turns the other way.

The sentence after しかも reports a fact. It does not carry a request, an invitation or what you have decided to do.

• × この店は安い。しかも、ここで食べよう → この店は安いから、ここで食べよう