Step 4: Brushes....
This was brought up earlier and while it is possible to do a good job painting with cheap brushes and roller covers, you can do a better job with good high-end ones (but they aren't cheap). In order to find out what makes a premium brush, I went to the most knowledgeable painter I know (my brother's spouse). He was a professional painter for quite some time and he knows his brushes ;). To paraphrase what he told me (I actually took notes so I could get this right and for my own future reference):
If you're painting with oil based paint, you would want to use a "china bristle" brush (these will mainly have black bristles). If you are doing mostly fine varnish, the softness of the bristles of a horsehair brush would be better (blond bristles). The "heel" is the part that fits to the handle. A good paintbrush will have a well built heel and you can generally feel the difference between cheap brushes and premium ones. All good brushes also have an empty space where the bristles are placed in the heel. This space is made by a wedge and you can see the space if you check between the bristles. The spacing is where the paint reserve is going to go. Do your best to avoid brushes that have a solid heel (in these the bristles are usually glued into the heel with no spacer). Look for the same design features for a brush used for latex paint but the bristles should be polyester (better) or nylon. Handmade brushes, in general, are better and clearly say they are handmade to justify the premium cost. For both oil and latex though you want wooden handles and you want to see that the heel and handle are joined with nails.
When you're done using them they should be washed properly, combed , and wrapped for storage.
When you're looking for roller covers, the best cover for any but very smooth surfaces is lambswool. Hands down with no comparison, nothing else comes close, but you will have to pay for that quality and they may seem rather expensive compared to the other covers available. Composite covers are a very distant second. However, lambswool will hold more paint, leave a nicer finish, and last for many uses (with proper care). You are lucky to get 3-4 uses out of a cheap roller cover.
If you need to paint smooth and ultra-smooth surfaces then you want to use a solid-fill foam roller cover. It doesn't leave bubbles that last so you can get a finish that does not need to be brushed (combed) out to get rid of them. These rollers look almost like inking rollers. You usually find them in small sizes like 3" or 4". The 6" & 9" sizes are harder to find. The smaller sizes mount on a frame that does not have a cage, the 6" & 9" need a good quality frame with a cage (the spinning thing left on most rollers when they don't have a roller cover in place).