I think the main thing is to remember that graphics artists use concept art, photographs, line art... everything they can get their hands on so they don't have to guess any details. If you have say, a soldier in full gear and you need to draw that - then google the details and see what comes up. Then, you see the uniform and equipment, and drawing that based on actual drawings is a lot quicker than trying to invent all those details. Professionals don't make it up as they go along, so take a leaf out of their book, and see how much material you can gather before starting your next drawing.
Art package is really up to you - I tend to get on with PaintShopPro 9, which is like Photoshop but much better for pixel work IMO. The best art package to use is the one that you know the best, and one that supports layers of course. Think about how you would work out the shading and stuff before you do it. I often lay down a base colour, then layer shading and lighting over the top - that way you can easily adjust it later, try filters, transparency levels etc.
I would suggest getting a graphics tablet, even an A5 one like a Wacom Bamboo.
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