Before you buy, make sure your account can play ranked at all: League of Legends opens ranked queues at summoner level 30, with at least 20 champions owned and 10 Swiftplay or Normal Draft games played. Then enter your current rank and division precisely, because that is what decides which pros are allowed to duo with you. Choose your server and queue type, and pick how many games you want, from one up to five per order. If you are close to a tier border, mention it, since it can change which pros are able to queue with you.
Use the notes to tell the pro what matters to you. Mention your main role and your champion pool, the role you would like the pro to take and anything you want to work on, such as laning, jungle tracking or late-game decisions. Add the times that suit you, including your time zone. The clearer the notes, the faster your first game starts.
Once the order is in your dashboard, connect with your pro on Discord, agree on a time and add each other in the client. Voice communication makes a huge difference, so have a headset ready if you can. Most duos start the same day and spread their games over one or more sessions, at a pace you agree on together. If a planned time no longer works for you, tell your pro in the chat early so you can pick a new slot together.
To get the most out of each game, ask questions. Why did the pro back at that moment, why that item, why that objective and not the other one? After the game, a short talk about one or two key moments sticks far longer than any guide. When your games are done, leave a review and, if you enjoyed it, order another round of Pro Duo and keep climbing with a pro at your side.