You are in the beginning, stick with what you have and correct your procedures.
I have a similar enlarger and i was used to condensor head from my laborator 1000, now i have just diffuser heads.
I note that i now have to develop a little more and i can use a sharper developer like rodinal, fx37 or even beutler or fx1 without having a too harsh image.
The lens that you use is of great importance, try newer and 6 elements, i can advise you el Nikkor 50mm 2.8, the newer model.
Some books will be good to read... Adams, vestal, ctein, thornton, anchell, rudman, graves... But first you could get a older copy of Basic photography from Langford.