Personally, if I could only have one, I would use my 30/60 triangle, but that might be an unnecessary expense for you, so… pretty much anything that is flat, hard, and straight can be used as a straight edge. You also must, must, must have a straight edge! Even though you’ll be drawing over a grid, if you want neat lines, you gotta have at least one straight edge. If you want to use pen, don’t use a gel, which stays wet too long, or anything that feathers and/or bleeds - a technical pen will be best lower cost Staedler or Sakura Micron work fine. Colored pencils, which usually require more than an accidental brush of the hand to smudge, also work great if you want to color-code. 07 mechanical pencil that you have is 2 steps softer than that and will not be a great option.

2H is my standard, but most “regular” pencils are HB (“B” means soft and “H” means hard, so an HB is the middle between a hard and a soft), so the yellow pencil or. If you want to use pencil so that you can erase, (first of all, erasing on trace paper is not a fun time, but second of all) you have to find a pencil that is hard enough to not easily smear (H at the softest) but is soft enough to not tear through the trace and to create a line dark enough to read. If you don’t have drafting dots/strips/rolls available, masking tape will do just give yourself a little more paper than you’ll need to fit the map on, so you can tear the tape off if necessary. Once the graph paper is taped down, do not move it until you’ve finished all the maps! Unless you have a drafting table with a parallel bar or t-square (in which case you probably don’t need this lesson from me), moving the base layer could create differences in orientation of your lines on your tracing paper maps. You will tape this down, and then tape the trace down over as needed. Orient your graph along the axes that make the most sense to you - most likely this will be cardinal directions with x as North-South and y as East-West.

Personally, I would use the base layer as the most modern version of the city you want to create, as this will probably be the largest map, and then the maps on trace will work backwards to the oldest version of the city, but do what makes sense in your mind.

Firealpaca line tool curve