I used to go the gym since I was 16 then I stopped at 19 because of university (I used to do both martial arts and body building). Now I started again, and it's been one about 8 months since I re-started, I only focus only on body building. So basically i'm try to develop both mass growth and definition (I mean... I'm aware that there's to be some tradeoff between two of them).
I go to the gym at alternate days (like monday-wednesday-friday-sunday-tuesday-thursday-saturday... and i start over).
Broadly in the first day I do both chest and biceps, in the second day triceps and back, third day legs and shoulder, and then I start over.
I've noticed some changes in my body, so I think my work out so far is good, however in the last period i'm noticing that i'm a little stucked with the weight. It's a matter of resistence, as example if with the curl barbell I lift up to 15 kg (I mean performing correctly the exercise up to that weight) then if I try (as example) to lift 17 kg I still don't have the resistance to complete the exercise, with "resistance" I mean that if with the 15 kg i'm able to close correctly my arm (bringing the bar bell almost to touch my chest) when i try to put some weight more i can't close entirely my arm (but i'm still able to do all the repetitions, but not correctly).
Same as some other exercises (not all of them). In case like this is there some kind of support/auxiliary exercise that could be useful to perform? Or some specific training style one could follow? Could be somehow related to the diet too? (maybe a healthier diet, like more protein I don't know... just guess).
I'm just asking for general suggestion and reference. I could give you more details of my work out if you think they could be useful.