Resetting a tripping breaker over and over without finding the cause
A breaker that keeps dropping is doing its job; the fault is still there. Repeated forced resets stress the breaker and, in worn boards, can overheat the buswork behind it. Reset once after unplugging the circuit's appliances; if it will not hold, stop and book a diagnosis.
Buying the appliance or fixture before checking the ceiling or the board
The induction hob that needs a dedicated circuit your DB cannot spare, the chandelier your gypsum ceiling cannot carry, the dimmer your LED lamps do not support: all cheaper to discover before purchase. A short survey visit or even photos sent ahead prevents owning hardware you cannot install.
Treating outdoor electrics like indoor electrics
Indoor-grade junction boxes in flowerbeds, unrated extension cords feeding garden lights and balcony sockets without covers all fail the same way: moisture gets in, the RCD starts tripping, and the search for the wet joint costs more than proper IP-rated fittings would have. Outdoors, specification is the economy.