Whether you keep it simple or more complicated, making a creative travel journal during your trips is great fun.
My mother used to make scrapbooks when she was back from a holiday. It was in the pre-digital days, so she had to wait until the film rolls were developed. When time passes we might forget things.
Nowadays we are fortunate to have access to smartphones and small digital printers so we can work on a travel journal during the trip. It is one of my main creative travel journal tips: work on it every day.