I use 2 of the smaller filters for 9 years now and rarely have leaks, so here's what I do... (1) use pre filters so I only open the main filter about 3 times a year (2) order plenty of spare O rings from China/eBay as they are cheap but take a good while to arrive (3) I use ptfe tape by running it once around the filter head and then put the O ring over it (4) l use WD40 silicone lubricant (Screwfix sells it) and rub it over the O ring with my finger. Not sure if this stuff is aquarium safe but I use so little of it, I don't believe or notice it getting into the aquarium water. (5) when reassembling the filter, I near fill the canister with tank water before putting the head back on slowly and carefully. I generally do not have to prime the filter this way (6) when it is all up and running again, I watch it very carefully for leaks over the next few hours.
As I have said so far this has worked for me- but may get home from work tonight to find my lounge flooded