For sketching, Moleskins are way way way overpriced in my opinion. Get a sketchbook from Barnes and Noble or one of those places. I got some for $5.99 each. They look like books.
I use a fine tip Bic Ballpoint Pens. I buy a box of them at Staples and they are also pretty cheap. They let you get a really nice skinny line plus you can ghost lines on the paper which a gel pen can’t do.
The next step up Pilot Hi-TecC pens. They do very very thin lines and flow really well. Not as good for sketching but great for overlays.