Candles are extremely versatile, you can do many things to an individual candle to help produce the desired outcome.
Something I like to tell people is that specific color that applies to particular psychological effects is not the only thing you can try, an easier one for beginners might be to try carving your spell or a few words into the side of a white, grey, or brown (neutral colors) candle that expresses your intention. Cast a spell with it.
Also something I like to suggest for beginners is a good luck charm. Find a little piece or trinket you hold dearly or have some kind of sentimental connection with, charge it, and take it with you to interviews.
Now working with oils aren't my strongest point (herbology and all that lol) but they are extremely useful in general practice even to beginners. So take your pick, my suggestions and WhiteRaven's are each good and easy to use. Luck spells and luck magic is generally fairly easy to use and work with, and rarely has particularly difficult consequences to handle in the long run.
Just be careful with whatever you do, don't be scared to explore your options a bit, again these are only 3 examples out of hundreds of solutions you might could look to.