While packing it is a good idea to know what to bring. It could be cold, hot, or raining. A way to check what the Prague weather is going to be like is to check the weather report for the days you are going. Prague weather in July may be a bit cooler than you would think in the summertime. Just like everywhere else it might rain so pack a raincoat and umbrella to be on the safer side.
If you want to experience Czech culture then check if there are any cultural programs, events or music festivals happening in Prague. If yes, then book your tickets for the show well in advance. One of the events they have in July is 'Prague Folklore Days' where you and your family can enjoy some folk music and dance.
Prepare a list of things to do, attractions to visit. Don't forget to add these attractions in your list: Prague Castle, Charles Bridge, Astronomical clock, Old Town Square. Remember, the best way to explore Prague is on foot.
You'll definitely need reservations in advance for your hotel, flight and you might pay more for it during the summer season.