It is most important to focus attention and effort on the critical task.
Make sure you know your Critical Path. At any time, there is only one critical task in work. This task currently has the greatest impact on the completion date of your project. If it is delayed by one day, the project is delayed by one day. If it gets done a day sooner, the project will get done a day sooner.
This may seem obvious or it may seem irrelevant, but it is the most significant factor you can influence. Influencing it can be as simple as asking about it every day. One day may not be a big deal, but constant attention to the active critical task will add up to a fast project. Not paying attention to it will almost definitely bite you.
There may be other near critical tasks that threaten to delay the project. Be aware of them and keep an eye on them. Don’t feel you have to watch everything.
Keep it simple.
Always watch the critical one.