At the end of each working day, I run a batch file on my computer which loads up a fresh copy of a .txt checklist. I work through this list top to bottom, deleting each line as I complete it. This serves two functions: practically organising things and setting myself up for the next day, and trying to switch my brain and body out of work mode (admittedly to mixed success).
Here's what's on that list right now:
How was today? I update my bullet journal and review each item for today. I try to give myself a gut 'how do I feel about this?' on each -- very negative, pretty negative, neutral, pretty positive, very positive. More than anything, this actually helps me recognise the preponderance of good (or at least 'not really bad') things even if I'm frazzled and grumpy.
What's tomorrow? I review my calendar/task list for tomorrow. Brief, as I usually have a pretty good handle on things.
Review APB -- ensure settled APB is 'Another Project Board', my main task Trello board. I glance over it and organise anything that's out of place. This is mostly a brief attempt to reassure myself that I have a handle on things and don't need to think about them until the next time I'm due work on those tasks.
Capture work Have I worked on anything that I should note down somewhere? This is largely to future-proof against times when I'll need to update my portfolio or give an account of what things I actually did when I worked somewhere. I struggle to do that in any detail retrospectively, so now take notes as I go. It also serves as a nice sense of 'hey, I did these things!' along the way.
Update timesheets This is the step where I update my sprint tickets if I haven't already. For contract work, I use an invoicing platform. When I incur some billable time, I create an invoice at the end of that day, scheduled to send automatically at the end of the month. Then, at the end of each day where I've done more billable work, I edit it immediately to keep it up to date. (I keep my own separate records in case things go squiffy.) This way, I don't have to worry about remembering to invoice on time -- it all just goes out in its turn.
Clear desk I tidy everything away from my desk and reset it for the morning.
Check and respond to message channels (no more than 10') I spend up to ten minutes replying to (usually personal) messages. Less necessary when I'm already in a 'high noise' cycle, but fairly vital when I'm in 'low noise' mode and being much more hands-off with communication.
Close down programs Close down everything except the text document I'm using to check things off. A digital desk tidy.
Change lights My desk lamps are set to a different colour temperature when I'm working. Shifting them out of that mode is a nice visual mode-switch.
You are done with work for the day I literally say this (well, 'I'm done...') to myself three times. I can't remember where I read this -- the person who mentioned it noted that it felt as weird and awkward as it does to me -- but I do find it helpful, as someone who struggles to 'shut down', to make myself go through this ritual.
Set computer shutout timer I set my computer to shut down in 15 minutes. I don't shut down right away because I might think of something I need it for, or otherwise come back to play games, but this is a nice forcing function to step away from it.
Leave the room, read for at least 5 minutes I think of this as a 'firebreak' activity, trying to pivot my brain to a different mode (something which, again, I struggle intensely with). It also means I don't go straight to playing games at my desk after work. I don't strictly limit this firebreak activity to reading -- cooking, walking, or if I have some evening commitment all work just as well. The point is do go and do something that engages me right away and isn't work. The more tired I am, the harder it is to untangle my brain from all the perceived-open loops that are still running.