Dosing & Potency
You can't see the strength, it's higher than you'd guess, and less is genuinely more.
On an unregulated market you're dosing blind. There's no label, no percentage, no batch consistency. The single most useful habit you can build is to stop treating "a normal amount" as a fixed thing and start treating every new batch as an unknown.
It's stronger than it used to be
The cannabis on the UK street market today is, on average, substantially more potent than a generation ago, and the CBD that once partly balanced THC's effects has largely vanished from it. STRONGEvidence strength Average THC in cannabis has risen markedly over recent decades, while CBD in street cannabis is now negligible, so the typical product is both stronger and less balanced than it used to be. Sources: UK seizure analysis putting sinsemilla ("skunk") around 14% THC with near-zero CBD (Potter et al., 2018), and a global review of rising potency (University of Bath, 2020). The practical upshot: if your reference point for "a normal amount" is a few years old, it's probably out of date. Higher potency means the same quantity hits harder and carries more risk of the acute stuff like anxiety and greening out. There's more in What's In It.
Start low, every time
The rule that actually works is dull and reliable: start low and go slow. With a new batch, or a new source, or a new route, take noticeably less than you think you need and give it time to land before more. You can always have a bit more. You can't take the last hit back. This matters most with the routes that are hardest to dose, edibles and concentrates, where the delay or the sheer strength catches people out (see Safer Routes).
Why moderation is the practical play
The case for using less isn't a moral one, it's a self-interested one. Lower, less frequent doses keep your tolerance down, which keeps the effect enjoyable and keeps the cost down, and they keep the risks smaller across the board, from acute anxiety to dependence. Past a certain point, more cannabis rarely means a better time. It just means a bigger tolerance, a bigger bill and a bigger downside. Using less is usually the way to get more out of it.