～ながら is used to convey the idea that an action is being performed WHILE something else is occuring simultaneously. Therefore, both actions occur at the same time and you just have to decide which one you'd like to mention first. In English as well, you may say either "Do you watch TV while you knit?" or "Do you knit while you watch TV?" １．ラジオを聞きながら、歯を磨きます I brush my teeth while I listen to the radio. ２．ご飯を食べながら、新聞を読みます ⇒ 新聞を読みながら朝ご飯をたべます During the meal, I read the newspaper. // As I read the newspaper, I have breakfast. ３．歌を歌いながら、皿を洗います I sing as I wash the plates. ４．電話を〇〇ながら、セーターを着ます ⇒ 留守番電話を聞きながら、服を脱ぎます As I talk with X on the phone, I put on a sweater. // As I listen to the answering machine, I take off my clothes. ５．友達と食べながら、話します I chat while eating with friends. ６．電話しながら、歩きます I walk while I'm on the phone. But you may also want to say: "I'm on the phone while I walk" 歩きながら、電話します。

For us, the Japanese people, we understand these sentences that the person have two actions at the same time. So, the answer of "whinch action is the first", it depends on the situation and her/his costom. For example, about 2, Someone starts reading newspaper, then his wife serves the breakfast. Someone starts having the breakfast, then starts reading the newspaper. However, 2 actions are done in the same moment. Since my English isn't still advanced, I would translate "I read the newspaper having breakfast / I have breakfast reading the newspaper. I think there isn't a big defference between two sentences in English, either. I hope this helps you.