The spell featured in the link above looks pretty legit to me. I have cast similar spell (just changed it slightly and adapted it for my own and their needs) for someone in need here, and they just reported to me that it is working.
Most luck spells are a mixture of showing the universe you want good fortune and a placebo to focus on the positivities in your life.
Here's something I'll make right now and add it to my own Grimoirelater:
Good Luck Charm - Easy Difficulty
Make or find something. Anything. It could be a ring, a rock, a necklace. Something of personal value or worn often works best. Hold it close to you in both hands and close your eyes. Imagine every time in your life when you felt you were lucky and fortunate. Imagine all the times in your life you were happy and felt rewarded. Imagine these thoughts as orbs of light inside your head, and imagine them coming together in a single form of energy. Imagine this energy traveling down your neck, arms, and into this object. Say something like: "Magic and the universe I need some luck, while I have this make it stuck!". Then open your eyes and carry the object when you need luck in your life. Try to use it as little as possible but only when you really need luck the most. Otherwise you'll get use to "good things" and feel like you need it every time you are not wearing it.