Play along with acoutic guitar or piano/keyboard. Not electric guitar. (this comes later when your voice is trained) Smoking is a big no-no. Certain foods are a no-no. (before practice, such as greasy food, and startchy stuff) Warm tea is a yes-yes for warming your vocals up. Singing a "style" that suits your voice is a yes-yes. Singing along to a scale UP and down Is a YES. And there are numerous Methods of warm ups you can use. Here is me on youtube;
Not actually sung at my best, i prefer it to be on cappo on third or second for this one.