It helps immensely to use OEM spec fuel injection rated hose, as opposed to just basic parts store fuel hose. OEM quality hose FI rated holds up better to the current fuel "brews" sold these days, including ethanol fuels. Low end fuel hose tends to shrink fairly rapidly in the presence of modern fuels, effectively reducing tension from whichever hose crimp you use, leading to leaks. Measure the hose diameter at time of install with precision caliper then a year later, and you'll see it.
As for the hose crimps, this forum would have you believe crimp types are inferior to screw type, which simply isn't true. BUT you must use a full 360 degree overlapped type sized properly for the application, such as made by Oetiker, which will happily maintain proper tension for years IF the hose doesn't shrink. This type of crimp is what's successfully used by the millions with automotive OEMs, in the Morgan submersed fuel pump module, and millions of homes that use PEX tubing plumbing. As the crimp type takes more care in selection, sizing, and installation, a screw type is probably best for most home mechanics. And a screw type crimp is easier to nip up once in awhile, though you can certainly do the same with a crimp type.
But really the underlying issue is the hose shrinking in diameter over time, so start there.
