All you really need is a pencil and a sketchbook!
However, most urban sketchers like to delve into other materials. Some common ones are:
Pigment markers, sometimes called fineliners. These are disposable pens containing pigment ink that is waterproof when dry, allowing for the application of broad tip markers or watercolor over them. They come in a variety of point sizes. Popular brands include Pigma Micron and Staedtler Pigment Liners.
Fountain pens. Many sketchers like the feel and line quality of fountain pens. These come with a variety of point shapes and sizes, as well as different filling mechanisms. If you want to use markers or watercolors over their lines, you should look for the ability to use water resistant ink (like Noodler’s Black) or waterproof ink (like De Atramentis Document inks, in various colors). This usually requires pens that can be filled by dipping into bottled ink, rather than using a cartridge (many pens offer both options). Decent fountain pens start at under $20. It pays to read reviews. Goulet Pens and Jet Pens are good sources.
Alcohol based and water based markers. These come in a variety of colors, tip shapes and sizes, and are often used for blocking in colors or tones (in place of watercolors). I believe alcohol based markers are more popular among urban sketchers, but both have their advantages and disadvantages. Here is an article outlining the differences.
Watercolor. Many urban sketchers use pigment markers or fountain pens together with watercolor. Most sketchers carry small watercolor kits. They can be used with traditional watercolor brushes and a small water container, or with water brushes, that contain their own water supply in a squeezable handle. This is a nice, inexpensive watercolor set to start with. Pentel makes good water brushes.
Sketchbooks. Sketchbooks come in a wide variety of styles, shapes and, most importantly, paper type and weight. If you are using watercolor, you want a sketchbook with reasonably heavy paper (preferably 140lb/300gsm or heavier), or that is marked for watercolor. Markers are also best used with certain kinds of papers. You might try searching YouTube for reviews and recommendations for sketchbooks suitable for alcohol or water based markers.
Ruler and/or triangle. These commonly used drawing tools can be handy when drawing architecture and related elements. (Hint: it’s not cheating, they’re just drawing tools!)
Misc. Portable stool or folding chair (if you prefer to sit as most sketchers do). Hat, sunscreen, something to drink and anything else you would like to have for spending three hours outside.
The demo sketch for the workshop will be done in pencil, fountain pen (Twsbi Eco) with waterproof ink (De Atramentis Document Ink, brown) and watercolor.
Additional Urban Sketching Info
Local Official Urban Sketchers Groups
These are groups that go out sketching once a month. They are a wonderful way to enjoy urban sketching in the company of others. They are friendly and welcoming, and most people are not at a high level of ability, so don’t feel intimidated. Always free.
Urban Sketchers Delaware Facebook Group. They go out on the 2nd Sunday of the month, from noon to 3:00 pm. Unlike other official Urban Sketchers groups, they vary between the three counties every month – New Castle, then Kent, then Sussex, then back to New Castle and so on.. They announce their location a week or so in advance.
Urban Sketchers Philadelphia Facebook Group. They go out on the second Saturday of the month, in various locations in Philadelphia, usually in Center City. They announce their location a little less than a week in advance.
Urban Sketchers International The parent organization for the official Urban Sketchers groups.
Urban Sketching Books – Just a few that I like and recommend. There are others.
The World of Urban Sketching by Stephanie Bower — Bookshop.org link — Amazon link.
The Urban Sketching Handbook Understanding Perspective: Easy Techniques for Mastering Perspective Drawing on Location by Stephanie Bower – Amazon link
The Urban Sketching Handbook 101 Sketching Tips: Tricks, Techniques, and Handy Hacks for Sketching on the Go by Stephanie Bower — Amazon link