I am not sure what you mean by practical advice. I was on the Paradise in September on back to back sailings so I did go to the ports you are cruising.
First advice I can give is go with an open mind and relax and let the crew take care of you.
Do not try to do everything that looks fun because you will just wear yourself out. Find a few things you really would enjoy and focus on those things.
Read the Carnival Capers every day. It will tell you of the times and locations of everything onboard the ship as well as dress code for the night. It will also list the specials for drinks or souveniers.
On the Paradise the majority,not all, of lounges are on deck 9 and you will find them by walking Carnival Boulevard.
The main pools, buffet, pizza and ice cream are on deck 10.
The gift shops on the Paradise are small and get quite crowded and are on deck 8.
If you want to see the shows in the main showroom go early to get a seat because there are a lot of poles to block your view.
Once you set sail you will leave and board the ship from deck 3 in every port.
If you like hand carved wood gifts than shop in Roatan.
Belize is a 25 minute tender to and from the ship.
If Grand Cayman has a lot of ships in port they all tender into the same pier area so there may be long lines of people waiting to board tenders.
The Paradise is a beautiful ship. The crew does a good job and are very friendly. Have a great cruise.