Many years ago, I adopted the "just do it" and "touch it once" approaches to things like incoming mail, incoming emails, to do lists, etc. after attending an organisational/planning/workload course that work organised for us all.
Rather than constantly organise and plan, the idea is to "just do it", i.e. with incoming mail, the plan is to touch it once, i.e. look at it and decide there and then whether it needs attention and if not, just ditch it. Then if it needs attention, if at all possible, just do it! Same can be applied to email in-box - either reply, action or delete it the first time you see it. It means you don't keep wasting time going through your physical or virtual in-tray, re-reading documents/emails, etc that you've already looked at once, but now need to look at again, and again, etc. It saves a massive amount of time.
Following that is your "to do" list management - rather than keep looking at it, re-prioritising things, re-ordering it, re-writing it, all of which wastes a lot of time, just aim to "just do it" there and then, reduce the size of your to do list. Takes a while if you start with a long to do list, but you will quickly see it reduce in size, and you can usually end up with a very short to do list which fits in nicely with the "just do it" approach, where nothing gets added to the list because you do it as soon as it comes in.
Obviously you still need some kind of monitoring/status tool for things which you can't currently do, i.e. when waiting for something/someone else to do their bit, but those things wouldn't have been on a to do list anyway, as you couldn't do them!
Nothing like the feeling of an empty in-tray or an empty email in-box. It's a bit like the old adage of a "clear desk is a clear mind". We all waste so much time, energy and mindspace on organising and re-arranging lists and piles of stuff that don't actually need attention and instead just need binning - it's a great start to ditch all that "background noise" as the starting point for getting on top of your workload management.
There's also another idea of a matrix, i.e. allocate everything to be:-
Urgent and important
Not urgent and important
Urgent and not important
Not urgent and not important
Starting point is to remove the not urgent and not important from your in box/in tray - bin or delete those first! No one cares!