First and foremost I always start by looking-up reference pictures. It's always good to know how your objects look like before you draw them, especially if it's something historic, like a dinosaur. My dinosaur is based on a Utahraptor. The most up to date information about them are that they were covered in feathers, so that is what I did. I also like that appearance more than how they usually show them in movies like they are some scary scaly monsters. I much better prefer the "bird" look.
Next, I sketch out my concept. How I want it to look like, what the characters are going to say, what onomatopoeia would best fit. Then when I'm satisfied with that, I make a more detailed sketch and change a few things to better the comic. And finally, I finish the comic. With all the final backgrounds, line-art and shading.