I’d say that really depends on you. Manifesting isn’t that hard—what’s hard is to find the faith to believe it can be done. And without that faith, manifestation won’t work, so it’s a bit of a vicious cycle.
You break that cycle by practicing a lot, meditating, honing your skill to focus and visualize, etc.
Start with simple exercises that don’t have any stakes. My favorite is cloud evaporating. On a sunny day with a few clouds in the sky, lie in a nice pasture (or on the lawn in your front yard) and pick a nice little cloud. Start really small.
Now will this cloud to evaporate. Let your vision blur and “see” the blue sky without that cloud in it. If you do it right, the cloud will get a more defined outline as if a shadow is attached to it. Then at some point, you’ll see “through” the cloud to the blue sky behind it. Once you get there and can hold that image, the cloud should evaporate very quickly.
You can test your assumption that you were actually the cause of the evaporation (and not just a gust of wind or whatever makes clouds evaporate naturally) by observing the other similar-sized clouds in the sky and seeing how fast they evaporate (if at all).
If the ones you pick go a lot faster, that’s pretty good evidence you’re doing it. You won’t believe what an elated feeling it can be to realize: WOW! I DID THIS!
And then you move to other things from there. Visualize finding a beautiful feather on the ground and start looking at your environment with awareness so you won’t miss it.
Or visualize a dollar bill on the ground. Something small that won’t overtax your faith to start with.
Super important: When you actually succeed, thank the Creator/Spirit/Goddess/Jesus/whoever you believe in. Gratitude is an essential ingredient. And don’t just pay lip service—you need to feel the gratitude for real, and deeply.
Another one of my favorite techniques is the Goodwill Manifestation. I love it so much because it is completely benevolent, and lots of good things can come from it without you actually asking for anything.
The more you practice, the better you’ll get. And before you know it, you’re off manifesting.