The brain is as good a resource as any.
Over the years I've created cities and towns, entire planets even.
What you need:
1)The back of a door, preferably unpainted wood or painted in a light color such as sand, white or sky blue.
Table tops or large wooden boards are also acceptable as are sheets of paper, including as hysterical as it may seem, the back of large wall maps. (I've used all the above).
An old kickball or other smooth surfaced ball or an old globe, paint it over with a flat paint. These work well as planets.
2)Several markers, red, black, green, blue, yellow orange and others. These will be used to indicate traffic lights, bus routes and things of that nature as well as the streets themselves which I tend to draw in black.
3)Time, lots of spare time,
4)A world almanac or an atlas or even better, both. These help you with town names and street names. The almanac includes people, so you can get more street and village names,
5)measuring sticks, they help draw straightish lines.
6)imagination... I really can't stress this part enough, you really need a vivid imagination to create your own unique city, town, municipality, state, country, planer, solar system etc.
You can draw freehand for islands and then create the streets by drawing lines that extend clear across, or which stop at various places such as parks or cemeteries or universities or shopping centers and the such.
A good working plan will include schools, both private and public and at various levels, the grade schools, the middle schools and the high schools. High schools should also include at least one vocational or trade school.
There should be churches and synagogues and mosques and Buddhist temples and other places of worship including the Agnostic House of Heathens, located oddly enough on Church Road or on St.Ibbybibbybop Avenue.
There should be a prison....I like to keep them along a river or ocean front space.
Be sure to label things such as government office areas, police departments, fire departments, gas stations,
And a few hospitals, religious, non religious and public.
You can also create your fictional city based on an actual city. Make slight adjustments, add a river, take what is currently uptown, make it downtown, move a hip happening area from the west side to the east side.
Without true imagination however none of the above will be of any use.