Here are a few tips and examples of what a well-designed chatbot might look like.
On desktop:
On mobile:
Both messages can be used to link to the same chatbot but differentiating between mobile and desktop makes sense since the open chat version performs better on desktop.
Make sure to adapt them to your brand and use different welcome messages for different chatbots.
Typically a good chatbot consists of 4 - 8 questions. Much more important than the number of questions is their content though. Make sure to only ask questions that actually add value by making recommendations better and giving users a more secure feeling.
The opening:
Make sure to greet your users first! If possible, offer different services at this point e.g. by integrating your customer support live chat.
The first question:
Offering different options: