Consecration: render holy by means of religious rites
There are tools that are used in a ritual and it builds energy in them to have them comsecrated according to the path that you walk. It also builds a link between you and your tools, it is an interesting thing to say the least and should be done in a private manner yet still as a manner of placing your energy into them so that they along with your guidance may accomplish many higher things.
Purificatioin: the act of cleaning by getting rid of impurities
Alright, purification should be self explainatory. The impurities in things can damper your magic and there are various meditations that you can perform to rid yourself and your tools of impurities. The best way to look at it is a grass stain on white cloth. You will get it out by a stain remover. Well our spiritual stain removers are simply chakra cleansing meditations and meditations to cleanse your tools. This should always be done before and after a ritual to make sure that everything on the magick stays "clean".
Invocation: the action of invoking something or someone for assistance or as an authority
Invocation is more complex than the other two. Lets look at a coven or a ritual. At the beginning of a ritual, coven meeting or church service.. there is always a prayer sent to the deity that the person/people worship. This would be the invocation. Because they are calling forth a higher being not into themselves but for assistance in what they are trying to accomplish.
Evocation: to call something out from within
Evocation on the other hand is the opposite. Lets role play for a moment and say Sally is possessed. (possessions are not possible but it is the easiest way to explain.) Well at night Sally does a ritual that calls the entity out of her and she can speak with it. She isn't calling from an outside source, she is calling something from within her own body. It may or may not be for assistance or anything of that nature.
I hope this clairifys any confusion that you are having about this/these topics. IF there is any that you want me to elaborate more on just tell me and I will see what I can do.