First of all, lay a sheet of Nori on a flat worktop. Sushi is 60% visual so keep it as simple as possible. The more you touch and poke the ingredients, the more you alter the natural appearance and flavor of the sushi.
There is a very exact tradition of spreading the rice on the Nori that sushi chefs have studied for years. It's claimed that sushi masters can place the rice on the Nori and have all the rice grains laying the same direction (Hmmmm!). However, the principle is to spread Sushi Rice about the size of a tennis ball on the Nori without squashing the rice. Rice consists of individual grains (even when they hold together) and should be kept that way.
You should then place the sushi ingredients thinly across the middle of the nori. Go easy until you get the hang of it. If you put too many ingredients in the middle, you will have a hard time rolling the sushi, which you should now do, using your hands to gently form a 'sausage of rice' surrounded by Nori.
After you have rolled up the Sushi Rice, nori and ingredients, place a slightly wet sushi mat (you can get these at any Asian food store, or online) over the rolled up sushi and press evenly and gently, sliding your hands from side to middle. The idea is to create either an even circle or a square shape with your fingers. Press gently on all sides and, at the same time, in the middle. Then do the same on the outer edges of the sushi roll and then again in the middle until you have a good shape for the whole length.
Now all you have to do is cut the sushi into lengths. I've found the easiest way is to slightly wet the blade of a sharp knife and then cut right in the middle of the sushi roll. Bring the two halves side by side and then cut the two sections into equal thirds. That way you will get six even size pieces in only 3 cuts.
Place your sushi on a decorative plate or platter. Garnish with wasabi, pickled ginger and serve with a little soy sauce on the side for dipping.
Other ingredients you can use are: deep-fried tofu, pickled daikon (Japanese radish), seasoned gourd strips, shiitake mushrooms, asparagus (cooked), red bell peppers, sun dried tomatoes.
Try to pick contrasting colors; this is important because it makes the sushi appear vibrant and interesting. Use a rich red tuna beside a yellow omelet, or next to the green hues of an avocado or a cucumber. Be creative!