Perhaps if you are just starting out or stumbled upon this site not knowing anything about "the craft" you have a preconceived notion of what spell casting and rituals consist of. Spells are the same as praying. Here is the definition of praying straight from a webster dictionary:to address God or deity with devout petition. When we "cast a spell" we are telling Gaia or spirit or whatever you call it in your spirituality what we want and by completing the spell we are releasing energy that has been "charged" with our wish or intent. A ritual involves a bit more than a spell does and usually involves calling the elements and deities into the casted circle.
Some candles are chose for their color and others for their scent. Aromatherapy is also used in magick to trigger an emotion needed for magick. Sandalwood and sage are good scents to burn.
You can use any combination of materials. The best materials to use are ones that you already have. It's the energy you put into the spell that really counts. If you have a bunch of all the right materials and no concentration, focus, or direction it still wouldn't work.
Usually it is the materials that aid the focus, the atmosphere that aids the concentration, and the words that aid the direction. The atmosphere can be obtained with just incense and a candle. The words are up to you. Do you prefer to chant? A simple yet powerful chant works best. Do you prefer to give an invocation? Write something that invokes an emotion within and appeals to the spirit without. It's really up to you and what works best for you. I highly recommend keeping notes of what you write and what you do and if it works.
Before the actual spell/ritual is performed, you should take time to meditate or have a Ritual Bath. The purpose of this is to eliminate negative energies from your magickal workings and to better focus your mind towards the subject at hand. If you will be having a Ritual Bath you may want to add something to your water: bath salt, oils, flowers, herbs, etc. in corresponding scent to your spell/ritual. For example, if you are doing a love spell, taking a bath in rose pedals or rose oil will help to set the mood.
Casting
1) Set up your altar with everything you have chosen for the spell. If you do not have an altar you can arrange it in a circle on your floor.
2) Draw your circle- walk around the perimeter to ensure enough space- physically take your athame, wand, or sword and carefully draw your circle- light some sage, incense, or other herb of choice and go along the circle, purifying with the smoke.
3) Light your candles.
4) Call the elementals, deities, or other spirits that you would like present (everyone is unique).
5) State your purpose or perform your spell that you have prepared.
6) Raise the energy by chanting, singing, dancing, meditating, etc.-this is a very important step. Be sure to raise enough energy or the spell will be short lived.
7) Directing the energy by visualizing your want or need- this is the fuel behind your spell, without it the energy will not know where to go. Visualize and practice holding an object in your mind to become better at this.
8) Releasing the energy- this must be done. End your spell with a closing such as "as my will, so shall it be". This can be compared to the Amen said after a prayer in the Christian religion. The best way to release the energy of the spell is to forget about the spell and whatever the spell was regarding. Trust me this works.
9) Thank the spirits individually that you had invited.
10) Discard all used wax and herbs that have been empowered for this spells use.
I recommend beginners use this format. It will help to develop your spell casting abilities and to develop your own techniques.