If you can't do then , then simply make a paper wallet , send your Bitcoins to that adress and hide that paper . and .. welll it's that simple
Actually, it is easy believe it or not. You can use various techniques, but my favorite is the memory palace. Take the list of words, lets just pick a few: The Lazy Brown Fox. Now choose a location that you are intimately familiar with, such as your childhood home. Start at any location, say the front door. Imagine something for "the". I am picturing cookie monster eating a big T in front of the door. Get the sounds and smells to if you can. Hear the crunch, see the crumbs flying around, etc. Now step inside the door. I see Gilligan loafing about naked. Don't ask me why, because I don't want to know, but that sticks for me. Again include sounds smells etc. In the next room imagine something for brown. Maybe poop. But make it memorable, such as a bucket of poo being spilled over someone you care about. Again the smells sounds etc. Now in the next area of the house I imagine star fox flying around and shooting things.
You have to choose images that will work for YOU. Some say that the nastier, funnier, stranger, more explicit, etc, the easier to remember. I am not so sure, I think it just has to be something that will stick for YOU. Try it and you will be surprised how much you can remember. If you do it right then remembering a private key will seem easy.
On another note I agree that the Trezor and Leger are good options. The Ledger has a low cost option if you can not afford the higher priced model or the trezor.