As a natty bodybuilder for over 30 years for anyone aspiring towards fitness and starting at the gym my most important advice is

"Put the phone away and bust some ass"

I see way too many people (the great majority) completely sabotage their training by putting the weights down when it starts to get hard and get on their phone.

When the weights get hard is when the real set begins. If you don't do the hard reps you deny yourself the stimulus required for adapting to overcome the stress, I.e the growth.