Alright, the first you thing you must know in order to cast a spell successfully is that you need to know what you want the spells outcome to be. This includes but is not limited to. Help finding or getting something, help remembering something, a positive effect on your health, a positive effect on your life, a negative effect on an enemy (not recommended.) and also help contacting the next world. Now the second thing you must know is the three fold law. If you cast a spell that is intended to cause someone pain know that it will come back at you three times worse. Third we have focus. Now a spell isn't just going to work because go want it to. You must have the focus to make it work. This focus is the result of meditation. Meditation should indeed be praticed every day for the best results and it will take a different amount of meditation for each person. Without meditation there isn't much likelyhood of the spell being cast successfully. Lastly you will need to believe that your spell will work and that you are able to make it work.
A lovely and wonderful explanation...however Meditation is not a must, you don't have to do it every day, Meditation is used to experiencing the know, picking up on every detail that your senses give you, like the feeling of a pen brushing against your lips and the sound of your pets walking through the house.
Focusing on your desire of your spell work is more of a Visualization technique than a feeling the now practice. If you can imagine a pie, what it smells and what it would taste like then you pretty much have "Focus" down.
With your mention of "belief" whilst it is a minor part of the spell work, actually doing the hard miles is more important than hoping for the winning lottery numbers. No Spell is a quick fix or a simple ta da and wishing.
Overall I think this post is actual quite nice and simple for anyone starting out so props to you for writing in, its just not the only or whole way to cast a spell.