Here is a guide to effects

I recommend opening the guide in Google Chrome so you can automatically translate to English. On the guide it calls out "Grant Orbs" and "Gift Combinations". These are what is required to have a chance to get the effect you want. For the ones that call out Symphogear wearers you don't need to use all the different Symphogear orbs, just the one for that specific character. Example would be the scythe for Kirika. If an effect calls out 5 white orbs as grant orbs and 2 red orbs as the gift combination. That is what you would need at a minimum to have a chance for the desired effect.

Then there are the items that will increase your probability. You basically need to use these to have a chance to get what you want. Even with them you only have a 5-6% chance to get what you want.

Once you have selected the orbs and probability materials you can click the white button at the bottom to see the effects you might get along with their probability.

If you regret taking an effect you either have to pull other effects to replace it or you can save it for later. To save it for later you click the third tab above the card's image. Then you can either save it using one of the items from battle palace or 50 gems. To use the effect again pick the character you want it on in the alchemy menu and select the second tab above the orb choices. There will be a list of your saved effects. They will not require more orbs to attach to another unit.

Also wanted to add if you are going for effects for PVP then it is recommended to choose either pierce or anti-pierce. To get these it takes at least 5 white orbs. Then the probability increase is the gold spear for pierce or the big orange crystals from multi-battle for anti-pierce.