I too decided to join a gym and hit the weights for the first time in my life, any tips, things to avoid, things i should do as a beginner.
i recommand training 2 times per week, not more, and 1 excercise per muscle group
first day upper body something like
bench press (chest)
dumbell press (shoulder)
lateral pulldown (back)
one bicep and one tricep excercise
do 3 sets of 12 reps, dont bother the weight, fuck that, bother about getting the excercise right.
before the weights, do 10 minutes warmup on a bike or trendmill or moonwalker
after, doe 20-30 minute cardio on a preferred machine (i prefer bike)
do that for 8 to 12 weeks
like this, your body adapts to weights, and you wont stress the muscle to much. in the beginning, you lack strenght in positional muscles, doing it light enables them to grow
dont let people help you if you are stuck at the 5th rep to do 7 more, thats only works in 5*15exhaust schedules, for a beginner, its the best way to injure yourself
dont bother supplements, eat right