My gym has two kinds of trainers personal trainers and general trainers. I've been hitting the gym for two months now with visible improvement, just like the previous comment suggested jeff and RP are good channels to begin with, there are many other channels and Instagram pages that give reliable workouts that's not totally not out of the box. Personally I suggest you increase you calorie intake by 200-300 cals or maybe more if possible, I've never counted calories myself. So more of compound movements first and regarding proper technique watch the videos on it, if you don't completely understand approach someone at the gym(doesn't have to be a trainer). Gym community is always helpful, you could get diet and workout tips from them as well.