Robes, proper can be very intricate, with certain characters/sigils embroidered. A robe goes a long way in raising power, making a significant difference in practice. As does being skyclad (naked). There are a couple of reasons for having specific ritual wear set aside:

a) to remove yourself from the affairs this world, or to prevent taking the day to day imbalances and programming of our waking lives from entering our ritual space. We leave the clothing of this world behind.

Being skyclad (naked) is wonderful to this purpose, as it strips us of the superficial, outward appearances we project. A robe dedicated to the art also works here but it has a further purpose:

b) A robe, made of natural material and dedicated to the purpose will become connected to your rites and will help you enter the ritual mindset when worn. It also helps maintain power raised, both from self and that which is ambient. The color one selects for a robe is very important, as it denotes the currents to be retained and therefore how the aura of the practitioner is to be aligned.

It is here recommended that before and while you are in the process of making your robe that you work skyclad, at least in your personal praxis, that you come to the gods of your craft just as you are, no more, no less. Learn first who you are, as nature made you, and ordained you. Once the mysteries of your natural body image are made known to you. Only then will you be ready to work the power of your body as a magic(k)al tool of the finest quality. Then will you gain the most from your robe, as it absorbs and concentrates the power of this mystery. After one has taken the time to adjust to the robe, they may embroider it with thee characters of arte, which are to be in red the color of personal power, or in the appropriate flashing color of the robe.

In some traditions, some colors are off limits (during group work). The two colors which tend to always be considered safe are:

Black: Absorbs everything, does not focus on anything specific. God for working with various forces and their modalities.
Robe of choice for the LBRP.
Robe associated with Kolyo and the dark halve of the year.

White: Pojects everything, radiates the power, does not focus on anything specific. Good for cleansing, and purity in general.
Robe of choice for the LBRH.
Robe associated with Goda and the light halve of the year.

Other colors are as follows:

Red: A color of personal power, blood and fire. Reserved for the High Priest as Lord of the Fire, an in this role, corresponds to Qayin. However, the exception to this rule is when one is to exalt an entity-form, current, or position associated with Fire, Mars or the sephira Geburah, though a specified robe for this purpose is more common within lodge settings than it is in circle work.

Blue: A color reserved for the High Priestess, representing communication, communal waters and flow thereof within the circle. The robe follows the same rule of exception as the Red robe but for the element of Water, the current of Jupiter or the Sephira Chesed.

Note: The gender-roles of the red and blue robes may be reversed in traditions that work predominantly on the inner planes.

Purple: Reserved for the Elder High Priestess, girt with the sword, or as is her discretion. A gender-queer color, of psychism, liminality and the third eye. It is the color of the HP "girt with the sword" because it is a) a symbol of the HPs given the fire of the HP and b) The color which she wears as an oracle, connecting to the egregore of the Coven and lineage, which is built up with the sword. Also used in some settings when invoking the lunar current or the sephira Yesod.

Yellow: A color representing will, vitality and solar force and it's associative sephira of Tiphereth as well as positions strongly associated with the element of air. May at times be worn by the Summoner or other 2nd degree Priest.

Orange: A color of vitality, heath and identity formation. Corresponds to the current of mercury and the Sephira Hod. Aids in contacting and working with power animals. Considered an alternative when red is not seen as appropriate and another consideration for a Summoner or 2nd degree Priest.

Green: color of growth and a vibrant earth. Worn for rites to stimulate personal growth, personal pruning, renewal, fertility and general connection to the Earth. Also worn on the more fertile Sabbats.

Sea-Green: for when Blue is not considered appropriate. Sea-green is a Water of Earth color, connected to the worlds oceans.

Brown: worn for grounding, fortitude, foundation, possibly for underworld work though many prefer black for this purpose. Used in representing the element of Earth and the sephira Malkuth, esp. if black is common enough to be considered normative during a rite.

At the very least, have some clothes set aside that have been dedicated and prepared for use, even if they be normal pants and a t-shirt, if you do not plan to go skyclad. This is not preferred but if it's what you have to work with make sure there are no brand-names or any thing on the clothes that would tie you to some institution, organization or identity thereof. This is also important when working with others. logos, mottos and so forth are egregores in their own right and should not be brought into group unless it is something all agree to be bound to by the work.