You watch a chef at the sushi bar slicing fish and you are thinking, "I could do that at home." But when you give it a shot, you realize it's not as easy as it looks at the sushi bar. Your fillet looks nothing like perfectly even strips the chefs pull out of the display case and your knives look nothing like their knives either. Don't despair. Here is a video of how how to slice the fish so that you can make lovely sashimi, nigiri, and maki rolls at home.
Other helpful resources
Here are my favorite chef's knife and boning knife. Both are very affordable. Here is how to keep them sharp. You might also want to check cutleryandmore.com (sometimes they are cheaper than Amazon).
How to buy fish for serving raw -- safety, bacteria and parasite risks, fish species appropriate for raw consumption
In the Boston area, I prefer to buy fish for serving raw at the New Deal Fish Market in Cambridge and at Captain Marden's in Wellesley.