With harm to none, free will to all
I've seen a range of variations but no matter how you say it, there's a basic rule. Don't harm anyone with your spells, remember that all are to have free will in what they do. Personally I like to add: and by the rule of three, so mote it be.
The "rule of three" essentially means that what ever I send out, I'm prepared to receive three times the effects. So if I'm wishing a world of hurt on someone, I best be prepared to receive 3 times a world of hurt. Simple really.
The "so mote it be" is said to be borrowed from the Freemasons. I say it to reaffirm my request and to end the circle/spellwork. It's a way of saying, "because I wish it so, it will be". However you want to phrase it is up to you.
Now that we have those established the basics and you've gotten the traditional warnings out of the way I have one more:
Be careful what you wish for! You just might get it.
I know that sounds silly but it's true. Dabbling in magic isn't helpful. Most people see some results then end up hurting themselves or others. Also, be fully aware of how your request could turn out.
Asking for a great man is all fine and dandy but if that great man belongs to someone else, your world wont be all that rosy.
I could go into detail at great length but the likelyhood that anyone would read it all and be fully aware of the gravity of the situation is miniscule. So instead I'll say this:
Remember that the deities (Gods and Goddesses) don't see time and language the same way you do. Be very specific and precise in your wording and intent! Now that that's been said, lets move on.
If you're looking for teachers or advise there's plenty of websites and local pagan shops. I suggest checking out witchvox. It's one of the largest and most used sites I've seen to date.
For reading or other webpublished articles check out Patheos's pagan portal. Fabulous authors and great information.
There's a great number of books for beginners from Silver Ravenwolf's how to ride a silver broomstick to wiccan for dummies.