Your work area
Regardless of whether you have a permanent dedicated hobby space or you do your painting at the kitchen or dining table or at your computer desk, wherever it is there are some ideas that apply to all of these set ups.
Keep it tidy
Try to limit what you have in your immediate painting area to just the things you're going to need. If you have 30 pots of paint out it's going to take you longer to find the one you want each time. If you have other models around then you're just inviting more trouble should there be an accident with a spill or similar.
If possible try to have a couple of small trays that you use. One should have the models you're currently working on, the other should be the paints you need for those models. This will make it easier to pack stuff away or move it around should you need to but also lets you keep your workspace tidy and organised.
Other than making your life easier for tidying, cleaning and reducing accidents, a work area with a small group of models and a defined set of paints on it can often help to keep you focussed on the project you're doing and is far less daunting psychologically than looking at an entire army all waiting to be painted.
I like to have 2 water pots on the go, one will be for cleaning my brushes and the other will be for thinning paint. You don't want to be dumping murky grey/brown water into your paints and then wondering why they're never as vibrant on the model as you'd expect.
My water pots sit right at the back of my painting area They're normally the tallest item on the desk so they're still easy to access, but I'm not reaching around them to get to anything. This minimises the risk of knocking over a half a pint of water onto the desk.
Change your brush cleaning water out regularly, it's easy to be lazy about this but if you change it whenever you get up for the bathroom, to get a drink or snack, or whenever a family member etc interrupts you then it's going to improve the lifespan of your brushes and it really doesn't take long at all.
Get a roll that you keep with your painting stuff, yes a whole roll, you'll use it every time you clean your brush, you'll probably be using it when you dry-brush too.
If you have plenty, then when you inevitably knock over paint or water you can minimise the spill quickly, it's less likely to ruin your current project, your work surface, your clothes or your carpet.
Whenever you wash your brush some water will remain in the "belly" of the bristles and if you store your brushes point up this will soak further down into them and can potentially damage the bristles, a brush rack will hold them horizontally and keeps them all in one place. There are some really cheap ones on ebay and at arts and crafts stores, it should probably cost you less than a couple of half decent brushes.
Thinning your paints is pretty much essential for good results in most instances, even when you're not thinning them you'll want to ensure they're properly mixed at the very least and that there are no lumps in there before you start slapping it on a mini.
Palettes can be broken down into two broad types, "dry" and "wet" they both have a purpose, at their most basic level a palette can be any surface that you decant your paint to before applying it to your mini.
Dry Palettes are often as simple as a ceramic tile or could be a purpose made palette from an art or hobby store.
Wet Palettes are only a little more complex they can be homemade or purchased, but the key concept is that a reservoir of moisture under a permeable membrane will keep your paints "workable for longer".
Ideally you'll want one of each.
You will want to protect whatever surface you're working on, you can use newspaper, a disposable tablecloth, a cutting mat, an A3 pad of paper, some left over vinyl flooring, or whatever else you have to hand. But do it, the one time you don't will be the time you knock over a pot of paint, just get in the habit.