How do you make thick and solid lines when stick and poke tattooing?

When hand poking solid lines, the line is being made up of tiny dots, and to get this to look good takes time, patience and skill

Solid hand poked 5RL line

Take your time. And try to poke as precise as you can on the line you made. Doing pokes as close as you can. Also, the bigger the needle you use, the easier it is to make a bold line, because it covers more surface area. A 5 or 7round liner, or even a 9 round liner, you’ll notice a huge difference in your progress. A stencil helps a lot. And remember: practice makes perfect.

Thick and bold armband source