Three basic things which manifest a spell along with knowlegde of your basics
Willpower- if you don't have the will power to cast the spell then it will fall short, you have to want to cast the spell
Desire- you have to desire the outcome of the spell for eg if you casting a protection spell then you have to have a clear intent of what you want and the need to have that objective
visualization, you must visualize your out come cause doing this helps the energy to follow your directions so you will have a better out come with less complications
In all of this please practice your basics- you CANNOT read your basics in 1 day and get them it takes practice.