Secret to using Jubilee clips.

[[159032]]

If you have ever tried to clamp silicone hoses you will appreciate that worm drive clips are not spectacular for sealing. The saddle for the worm drive is optimised for certain pipe diameters and work against forming a seal if they are out of range.
Fuel pipe clips, like the Mikalor, are a better solution. Yes they may be awkward to fit, but they work.

Demon Tweeks sell a range of clips at good prices. This worm drive clip doesnt use a shaped saddle LMA Stainless Steel Worm Drive Hose Clip

Mikalor are about £3 each Mikalor Stainless Hose Clamp

 

[MAURICE]

Try using plumbers PTFE tape wrapped a few times around the fitting before puting on the pipe. The tape expands in water and will help seal the pipe. Also you can wrap insulation tape around the pipe

 

[JumbleDuck]

I like Ligarex, which is a stainless strapping system used on old Citroëns. You basically make your own clip from new each time, using a special pair of pliers to tension. You can't re-tension afterwards, but I have never had one come loose.