You need to set up an MDE account if you have not already. You can access your account via an app or via the website. You will be going around Easter I guess, so you need to get onto making park reservations. This is a reservation for the first park you will visit each day, after you have been to the first park, you can hop to another park assuming you have the usual UK tickets.
You need to decide how many days you would like to book for each park, I tend to book more for Magic Kingdom and Hollywood Studios than I would for Animal Kingdom and Magic Kingdom. I don’t really think it makes any difference what day of the week you do each park these days, I generally go for a rotation.
When you open up the app each morning, there will be a very prominent suggestion to purchase Genie+, you are not going to miss it I can assure you. Over Easter, you might want to get onto this quickly (after midnight) as recently they ran out. You can only buy it on the day, but you certainly don’t have to buy it every day, that is up to you.
I don’t understand what you mean by best queues? To me the best queue is a short queue, but I don’t think you will see many of them over Easter. The longest queues will of course be for the most popular rides.
Be aware of virtual queues. At the moment there is just one for Guardians of the Galaxy, by the time you go, Tron is likely to be a virtual queue either as well or instead of Guardians. You need to be very very quick to get into the virtual queue.