The key to this isn't what you use, it is sheer force of WILL. I've found that clear visualization helps. If you can see in your mind what you want as clearly as if you were in front of you, that's when you've done effective visualization. This takes practice. I've also found that making my own incense, etc helps.

In seminary I took some alternate religious studies. One of the teachers was keen to point out that "magic" is an energy of emotion. She pointed to all the gadgets, tailsmens and components of spell craft and demonstrated that nearly all of them invoked certain emotions in most people. As symbols that the mind can focus on and engage on an emotional level. Meditation is one of the tools where the symbols of the spell are to be reflected upon and the feelings that those invoke are supposed (in theory) to relate to the spell in question and that the caster is supposed to feed upon and build up the 'energy'. In other terms. The spell has two phases (more actually, but for simplicity I say two). The first is like a capacitor where the spell caster goes through a period of building up a "charge" where the focus is on the symbolic that invokes certain related emotions or feelings. The duration depends on the spell and the caster. The second phase is the discharge where the energies are "focused" on the intended target (person, item, ailment, whatever) and the caster goes from focusing on the emotions to focusing on the target. Much of that is visualization of energy flowing. Different traditions have different visualizations of the energy flow. In many cases having a symbol of the object or person (say a written word, or even a picture) before the caster where the symbol becomes the target is used. The theory is that the symbolic item becomes the person or the target, is connected psychically to the target. This teacher also taught "effective prayer" where she demonstrated that a lot of prayer, what we say or recite, the objects we use in prayer (beads, stances, visualizing) are in fact "spells" however instead of calling upon energies from within we call upon energies from without (God, Allah, Christ, whatever).