Broccoli Rabe is not broccoli.

Prep your Rabe: Chop of the last 1" of the stalks and discard. Chope the rest into 1" pieces; stalks, stems, leaves, and florets. Wsh well by plunging into a bowl of cold water and rinsing.

To use: cook one of two ways: boiling in a pot of water or wilting in a skillet; either way will alter the bitterness associated to broccoli rabe.

a) if you are new to broccoli rabe: start by blanching rabe in 2 c. boiling water for 3-4 minutes. Too much water and the flavorful characteristics will be taken away. Cooking longer is not better~it will make your rabe mushy and unappealing.
b) wilting: start by sauteing onions, garlic, and other aromatics in a large skillet with oil, then add rabe. Cook another 8-10 minutes until rabe stalks are tender but still bright green. Add a little water to keep rabe from sticking to the skillet.

If rabe is still too bitter for your liking...definately use the pot of water technique to dispel some of those bitter compounds.

Regardless of your preparation technique, rabe benefits from additional accompaniments such as sausage, currants, pecans, capers, onions, garlic, beans, pasta, sweet peppers, vinegar, potatoes, anchovies, capers etc.