When I first started working out, I just did it randomly - bits and bobs on different machines, whichever were free or what I felt like doing.  Very sloppy all round!  I ended up joining a better gym when I was 16 and that helped.  It was more professional and I started to add structure to my training about the same time I got my diet more on track too.  I actually grew to know what I was going to do each day in the gym and what I was going to eat each day...not whatever was put in front of me or what I fancied in the moment.  I had a plan!
I figured out the right amount of food and how often to eat to start building mass.  I also started tracking how much I was lifting through a session and each day of the week for different muscle groups.  It soon became second nature but it's easier to write it down to begin with.  This was a major factor in me starting to see real gains.  My turning point was all about STRUCTURE and having a plan!  

If you too introduce structure and a plan into your lifting regime your gains will come and the weights you lift will go up and up, as will your strength and your overall shape and build.  So make that change now!!