Because you're wanting your minis to look passable (what I'd call "table ready"), here are a few things to consider:
Modeling Tools -
Opening Note: Because you're not looking to compete in Golden Demon or any other showcase, don't worry about pin vices or frisket or mitre boxes or needle files or anything like that. You want something that's going to be ready to play fairly quick so you're going to be
de-spruing, maybe trimming some mold lines and that's about it. You can get more tools as you get further into the hobby but what I explain below are the bare-basics.
1. As
Peredyne said, buy an all-metal hobby knife (doesn't have to be X-acto but if you want, you can). I stress all-metal because it'll last you much longer than plastic. You really only need #11 blades. I would consider all the other blade types for specialty purposes but not for what you want to accomplish. I woudl suggest NOT buying
GWs knife because you'll have to buy a specific type of blade for refills. Get a knife that has a twist-hold action for your blades.
2. I made the mistake early on of just using my knife to
de-sprue my figures. The knife would end up marring other parts of the figure as I cut pieces of the sprue or would cut my hands. Save yourself the trouble (and blood) and pick up some flush-cut nippers. Cheap is fine but you just want to make sure that they align well and that they're SHARP. You could try beauty supply places for cuticle nippers (Sephora used to have a really good pair but they don't cary the ones I have anymore), just make sure they're flush-cut as it'll save you time in trimming off the extra stumpy area where it was connected to the sprue.
Final Note: You might think about getting a fine-grit sandpaper if you're needing to smooth out mistakes and edges (600-800 grit), especially flat surfaces for Tau or Eldar tanks. Just a thought
Paints -
1. GW paints are good if you don't want to mix your own colors, don't want to spend a few seconds thinning with paint, or if you're going to be using
GW paint instruction books for your chosen army (very prescriptive from my experience). You can also use other mini paints as well, but their pricing is going to be around the same cost and the colors won't be exactly what
GW is putting out. My suggestion for just starting out, go by Michaels or your own local craft store and pick up some $2-$3 craft paints. They come in a WIDE VARIETY of colors and they're already pretty thinned out, almost ready for painting. You can buy tube artist paints, but I think for your level and just starting out, the lower price wins out over the amount of paint you'll need.
2. Base-coat color is important because paints are translucent (the colors underneath inlfuence the colors on top - especially true for reds, yellows and oranges). I've used
GW spray paints before and didn't have a very good result, but you can try out a few and see what you like. Make sure your basecoat spray comes in a color that matches the majority of your models. For example, if you're playing blood angels, find a base coat in red! It'll save you A LOT of time!
3. If you're okay with mixing your own colors, you only need a few paints - red, yellow, blue, green, black, white, silver and MAYBE gold if your army calls for it. Some folks have difficulty mixing orange and purple, so you can pick those up as well if you want.
A special note on brown: Brown can be hard to mix. I would suggest picking up a range of browns so you have some options and then mix other colors into them to pull out the color you want - (these are traditional names to the colors. If you're going with
GW or other mini paints, you'll need to match the colors)
Raw Sienna,
Raw Umber, Yellow Ochre, Burnt Sienna and Burnt Umber
Brushes/Paint Supplies
1. Don't start off buying expensive brushes. Because you're just starting, there are habits that experienced painters have developed over time to keep brushes clean and in good working condition. Unfortunately, I've lost too many brushes to dried paint and poor painting skill to recommend expensive brushes. I would suggest, again, go to Michaels or your own local craft store and pick up a multi-pack of brushes in differing sizes.
2. As far as shapes go, you'll want a medium round, a small round or detail, the smallest detail you can find, a medium flat, a small flat and that's about it. If you're working in acrylics, it won't matter much for you if you're using natural hair or synthetic (the white ones) but if you're going to use oil-based paints, use the natural hair brushes.
3. For a water cup, a coffee mug will do.
GW's water cup has the lid that grips your brushes which is good if you tend to forget your brushes in water, giving them a bad hair day

, but not necessary.
4. Some folks like to use wet pallets for their paints (paper towel in a tray of water). I prefer mixing on hard surfaces. You have a few options such as plastic trays from craft stores, panes of glass (a little dangerous?), plexiglas, etc. Something I picked up in art school - freezer paper! It comes in a big roll at the grocery store and is similar to butcher paper but has a plastic coating on one side. I cut a small piece off, about 5"x7" and tape it to the table or desk or where ever I'm working. Having a white surface is also good for diluting washes so you know how thin the wash is getting before applying it.
5. When adding water, I like to use a finger-pump spray bottle. The one I have was for a hair spray but I just suggest finding something that has the lightest mist possible so you have good control over the amount of water you're adding.
6. Have a good supply of paper towels for drying your brushes and getting your brushes ready for dry-brushing techniques.
Final thoughts
1. After using your colored basecoat, limit the rest of your colors to the flesh/hair colors (if any are exposed), black and white parts to the model, metal (guns, swords, etc.) Finish with a dark brown wash over the whole model to bring out the details and a drybrush of the main basecoat color tinted with A LITTLE white and that should cover it.
2. For your bases, they all have a little texture and because you're doing
40k, you can get away with a black spray basecoat, drybrush gray over that and then drybrush with a light gray on the textured top and you're done. In the future, you can invest in balast or flocking, but for now, let's get it on the table!
3. Batch-painting may be boring, but the repetative painting process will help you hone your hand skills and help you to get experience under your belt quickly. Start with only a unit (no tanks or anything like that yet) and work up in number and then variety.
4. Take breaks often. Your eyes and hands will get very cramped and tired for your first few sessions. And remember, if you get frustrated, walk away. No sense in cutting yourself because you were rushing and the knife slipped.
Any questions

, lemme know