For the first couple of weeks focus on what you like doing - what is comfortable for you? When i was starting out it was leg press. In the beginning, keep reps between 8 and 12, acknowledge that training to failure is when the muscles literally cannot move the weight even the smallest amount (you should do this every other set or so / rough guideline), don’t use machines for more than ten minutes at a time, and rest a couple of minutes between sets . Push-ups and pull-ups are a good place to start / nickels and dimes coined by David Goggins is when you super set pushups and pull-ups (super setting is when you do train a different muscle while the other one recovers and vice versa). It’ll become all you think about before you know it. If you want some homework - learn what is meant by RPE, RIR, and a workout split.