If I can give you hints (that took me years to find myself before the internets):
1) Get a pencil with a thick hard lead lead: 2mm and 2H
https://www.amazon.com/Koh-i-noor-5201CL-Versatil-Holder-Sharpener/dp/B0056AAFEU/ref=sr_1_5?s=office-products&ie=UTF8&qid=1489951393&sr=1-5&keywords=pencil&refinements=p_89%3AKoh-I-Noor
This is used to lay out fast and is easily rubbed out.
2) Bet a 0.5 or 0.7mm pencil with the twist rubber. THE TWIST RUBBER IS IMPORTANT, it allows quick corrections of small areas.
https://www.amazon.com/Koh-i-noor-5055-Mephisto-Profi-Pencil/dp/B0056A8Q3W/ref=sr_1_7?s=office-products&ie=UTF8&qid=1489951565&sr=1-7&keywords=pencil&refinements=p_89%3AKoh-I-Noor
This is to refine and finish your lines.
General remark on pencils:
Always get pencils with a clip, use it to reference it to your hand, the bigger the lead, the more important this is.
3) Get a few soft wood case traditional pencils (2B or 3B).
To fill in darker areas.
4) Tread softly.
You want darker, go over a few times. Darker still? Use a softer pencil.
5) Get good paper.
If you like have squares, photocopy a blank page of 0.5cm paper onto heavier copy paper (120gr).
Tune the copier to the lightest grey it can do with still visible lines.
6)Draw a lot. You just need to draw a lot. There is no secret.
I stopped for 10 years (3D Max and all that computer jazz) and it now takes me 5 hours to do what I could do in 1 hour - and it's worse!
Remark: Koh-i-noor is just one brand, and in my case, it's 50% cheaper in the local art shops than on Amazon.
