Other factors to take into account

Timing....you could observe the timing of the planets/moon cycle. Planetary hours/days etc. Some people plan the month/day/hour etc. for their rites. There are a number of books on tables of correspondences etc. I will reference them later.

Repetition....very basic CB is to repeat until the desired outcome has been reached. This is good for stopping smoking etc. You could observe numbers associated with numerology charts etc. A lot of CB rituals are available that give specific instructions about how many times the rite is to be repeated e.g. repeat 3 times for 3 days. You might want to use 9 candles for this, you might want to use 3 lit 3 times, or 1 lit 3 times 3.

Colour....I think colour can empower the rite if it means something to you. If in doubt use white. You could use two coloured candles, red inside and yellow on the outside. They are easy to make, just dip a ready made red one in yellow wax a few times (smiley) You could use two candles of different colours. For example if you're trying to stop pain in some way, migraines etc. start with red to pink to white, whatever helps you focus.

Words....Spells are words, you could write a chant, poem, use a poem you know, use the psalms from the bible. A quote, anything really as long as it is personal to you and feels right. You can repeat your chant etc. a specific number of times.