The best rissotto I ever made was the recipe in Gordon Ramsey's "Makes it Easy" cookbook. Some quick pointers from that recipe are:
bring 3 cups stock to a boil, then lower to a simmer.
In a separate pan (deep saute pan) heat some oil and saute some shallots for 2 mins or so, then add some celery, cook 2 mins. Then add your rice and saute for 2 minutes add 1/2 cup white wine and cook until the wine is absorbed. Then add a laddleful of stock to the rice and cook until absorbed, then add another laddleful of the stock. Continue until you are out of stock. I used medium to medium high heat.
Once the stock is all used up, I sauted some mushrooms and incorperated into the rice and then added some sour creme (the recipe called for creme fraiche or mascarpone) and mixed well. The results were a very creamy and moist dish.
Cooking the rice this way gave me some of the best tasting rice with a wonderful texture. One note though, the rice should be slightly al dente - firm but not hard. I hope this helps. Also what type of rice are you using? This makes a BIG difference in the final product.