When I try to pray, I cannot always pay full attention. My mind wanders many times. I am cautious about my prayers, but I still drift away in my thoughts.
When you read through the prayers recorded for us in the Bible, what becomes noticeable is that most of them are short and to the point. Many of us try to pack too much into one prayer -- perhaps because we save up too many things for our "prayer time" instead of taking a moment to ask God then and there for help.
When a need comes up, go to God in prayer about it as soon as you can. When there are many things to discuss with God, then pick one or two issues, pray about them, and then take a moment's break before returning to pray about the next few issues.
Finally, don't fall into the trap of ritualistic prayers. Pray in your own words about the things which are important to you at that time. This is your conversation with God. When it comes from your heart, then it will take more of your concentration to express it.