Regarding advice about buying ethernet cable and phone cord?

I just got an internet connection. I have never been online or owned a computer before. I want to buy 75 ft. of ethernet cable and phone cord to run from the phone jack and modem to my work area because I don't want any wireless technology due to health reasons. Is there any advice to help me choose? I got on Amazon and thought just to buy the cheapest but then thought there might be different designations or quality issues. Thanks.