Wow, what a great question! I do several things on a day-to-day basis, so the tools I use for those would probably make the list.
The first tool I could not live without are candles. I do a morning devotional almost every day, and I use a big pillar candle for that. It helps me to center myself and start my day with a dose of spirituality and calm. I also do a lot of simple candle magic. It’s simple, it can be quick to do, and doesn’t need a lot of extras if you really concentrate on your intent while doing it. For a busy mom of three kids, candle magic is where it’s at, lol!
The second tool I couldn’t live without: my mortar and pestle. I actually have more than one (I use one in my kitchen to make freshly ground pepper when I cook, lol!). When I’m working with herbs, there’s no better way to slow things down and really concentrate on the work you are doing than to sit and grind them together. Just remember that if you use one for any kind of poisonous herbs to keep it separate from the one that you use for herbal remedies and/or cooking!
The third tool that I couldn’t live without? Sea Shells! I use shells that me and my family pick up from beaches in so many ways! I use them to snuff candles out. I put sand or salt in them and use them to hold small candles, incense or sage for smudging. I’ve actually made candles right in the shells! What else? I’ve used larger shells to mix herbs. I’ve left offerings in them outside for the fae. I’ve used them in love magic, and in fact have all the shells that Mr.B. has ever found for me on my little “love altar” in my bedroom (which also includes pictures of us, dried roses and a heart shaped candy box).
I’d love to hear what supplies everyone else thinks is a “must have”!
As a newcomer I find my smudge sticks and stones to be very helpful. I like to smudge mine and my husband's apartment at least once a month to get rid of any bad energy and so everyone (us and the animals) can live in a happy and centered space. I also keep a clear crystal quarts over my front door to suck up any bad energy that someone might try to bring into our space.
My 3 must haves are candles, incense and a stone or stones
the candles help me guide my energy and focus, the incense triggers my brain and spirit and the stone(s) help me to ground 
I would have to say my must haves are candles, insence and my BOS. they are the constants in any magic or meditation I do. other tools come and go deoending what I do, but those 3 never change and are always there.
This was great! Thank you!
My three tools I couldn't do with out…A big white pillar candle, the kind in a glass – like you, I use them as devotionals. Since I'm home most days, I keep one burning a lot of the time, as a symbol of the light the Lord and Lady are in my life. I use others once in a while, but I use that big one almost every day.Incense. Living in an LA condo means I have a cockroach problem, it comes with the territory. So I very rarely leave food offerings on my altar. Instead I burn a variety of incenses chosen to please different aspects of my pantheon. I also use them in different workings and rituals.And finally, my tarot deck. I pull a card every day to focus on and ponder the meaning of in my life. Less as a way to tell the future or answer direct questions, more as a way to meditate and focus my subconcious. Whew, that was a long comment! Sorry for the wordiness!
This isn't really a tool, but I find access to some sort of quiet place in a relatively natural setting to be the most essential. I find it difficult to center myself when surrounded by four walls, no matter how much or little ritual and tools I use. Give me access to unpaved ground with stars above and I'm good to go (I was flat out miserable while stationed in Korea with no access to anything but a patch of grass in the PT field, with so many lights around that the moon looked washed out at its full).
I think the three I use most are:
- Candles, for all of the reasons you stated.
- Natural Handsoap, because many witches underestimate the power of simple ablutions before ceremonies, rites, and approaching Deity (and handwashing for more everyday and symbolic cleansing… even if you’re just having a stressful day, washing your hands can make you feel refreshed). I have a natural soap made with dragon’s blood resin that I use for ritual preparation.
- Pen/Paper
(also my “Laptop of Shadows”)
I LOVE your answers, especially about symbolic cleansing – and I feel exactly the same way: http://www.patheos.com/blogs/confessionsofapagansoccermom/2011/01/ritual-hand-washing-for-the-domestic-witch.html