Here is a small list of some of those little things you will always find yourself reaching for when doing studio work. Keep in mind that this is by no means an exhaustive list and there are some useable items I'll surely have forgotten to include. Feel free to add to the list in the comments section below.
Light Stands: Although there are some DIY solutions for a light stand, nothing beats the convenience, portability and diversity of this utilitarian piece of equipment--store bought. Specially if you have a tendency to work alone. They will become your assistant and extra set of hands.
If you have gone out shopping for stands you will see they range in price from about $20 up to $70 and $80. With light stands you actually get what you pay for. You just have to know what you need before spending too much money. For example; don't put a heavy mono block flash head and modifier on a $20 light stand. That's a recipe for disaster but these light-weight stands do a great job for portable speed lights.
As you grow your studio try to get a variety of sizes and heights. Short 18" stands are great for getting lights down low, 7 foot stands are great all-purpose stands and the taller, heavier 10 and 12 foot stands are great for back drops. Consider spring or air cushioned stands for heavier light heads. Don't forget some crossbars and support arms. They come in handy for background cloths, overhead lighting, reflector and flag supports, or just holding things up.
Clamps: Clamps are inexpensive--and indispensable. Clamps are also one of those tools that have a million and one uses. You see them frequently holding up backgrounds and reflectors but they can be used just about anywhere a second set of hands are needed. I've used them to secure cables, stretch out table cloths, hold up foam core boards of all shapes and sizes, even to tighten up clothing on a model.
Clamps come in a variety of sizes and styles and I suggest going to the dollar store and picking up a large variety of metal and plastic clamps. A good tip is this; the smaller the subject you work with the smaller the majority of the clamps you'll need. Metal "A" clamps tend to be sturdier but you have to be careful what you clamp. The sharp edges can cut or scratch whatever your clamping. For those situations a plastic clamp work better as it protects the surface from scratching.
There are also a variety of DIY stuff you can do with clamps. Put a 1/4-20 bolt on one of the handles and it becomes a convenient platform for gear that takes the standard 1/4-20 threading. A small ball head is one such idea. Attach an articulated hose with a second clamp on the other end and you have a positionable assistant that never complains.
Gaffer's Tape: If you don't know what gaffer's tape is it is a strong cotton cloth tape similar to duct tape but with a matte finish to avoid reflections. It can be rather expensive but once you have it you will always find a need for it. In a pinch I have used black duct tape but you have to worry about glare from it's glossy surface. Duct tape also tends to be stickier and can often leave glue residue on the surface it is adhered to. You can buy the cheap duct tape but that tends not to stick well.
Gaffer's tape has proven to be invaluable in repairing equipment that has failed (or broken) while on a job. Things do tend to break or come loose at the most inopportune times. Blame Murphy for that. A good example is with the metal clamps mentioned above. The rubber protective tips tend to fail, exposing a sharp edge. A couple of wraps of gaffer's tape and you now have a soft, safe tip again. It's also great for holding down the leading edge of seamless paper on the floor.
Masking tape is another handy item to keep around. While not as durable as gaffer's tape, masking tape is great when you need a temporary fix. I have used masking tape to hem pants, hold things from slipping and even on the bottom of model's shoes to save wear on a seamless white backdrop.
Foam Core Boards: A common staple for craftspeople, foam core boards are light weight, easy to cut and universally available in the crafts section of large department stores and art supply stores. The two most common colors are black and white but you can find them in other colors as well. For photography use the black and white colors are ideal. White boards make for great reflectors that can be cut to whatever size you need. Black can also be cut to size and make great flags and gobos.
These handy boards also make great backdrops and table tops for smaller objects. Because of their inexpensive nature they can be abused without concern and replaced when needed. One tip I give my students is to purchase one large sheet of black foam board and one sheet of white poster board. Glue the two together so you have one white and one black side. You can then cut this to size and have a multipurpose reflector/flag.
Electrical Extension Cords: No studio is complete without an assortment of electrical cords and outlet strips. Specially if you are shooting on location and the nearest outlet is on the other side of the room and there's only one available. Just be sure you secure your cords so no one trips over them. That's where gaffer's tape comes in.
Years ago when I used to DJ an essential piece of gear that traveled with me were small utility carpets. I would put them over the cables wherever anyone would be stepping over them, usually at doorways or isle-ways. As with any electrical equipment, safety is an issue. Make sure your cables are safe, intact and free of exposed wires. Don't try to save $20 by wrapping a split with electrical tape. If anything, cut the cord at the problem area and attach a new plug end. You'll maintain safety and now have two cords to work with.
White Boards and Markers: Having a small white board and dry erase markers seem like an odd item to list here, however, like many useful tools, you'll wonder why you never thought of it before.
A large white board can be used to keep track of momentary things like client phone numbers, things to buy, notes to self including production notes, messages to staff personnel, reminders, etc. A small clip board size white board is handy during a shoot for keeping notes. I use mine to keep notes for a shoot together with the shoot itself. Here's what I mean:
Let's say I have a particular lighting setup I will need to duplicate in the future. Once my lights are set up I not only take a picture of the actual setup, I also take a picture of a diagram and notes I've drawn on the white board. Later, when I import my photos into Light Room I have all my notes right there with the session shots. I also keep a home made white board in my travel bag. It's simply a half sheet of paper that was laminated. I scribble my notes, take a picture and erase the sheet for later use.
Miscellaneous Useful Stuff: Aside from the above items there are a few other things you should keep at the ready. Much of this can be kept in a small tool box or tackle box. Items such as;
- Safety pins and hair pins for pinning clothes and hair, obviously
- Rubber bands, string and clear tape have multiple uses
- Stapler and staples; both a utility stapler and desk stapler come in handy
- Pens, pencils and markers because they're never around when you need them
- Small note pad because you never have something to write on when you need it
- Small and large scissors and utility knife; plus extra blades for the knife.