@Simon-Bates I personally rarely let a bet run, but there's nothing wrong with doing so if you think you have decent value from the bet.
Hedging or partial hedging will remove some or all liability. If you're dripping in your backs then you could drip in your hedge bets as well.
If you want to keep it really simple you could just lay for the exact same stake as you backed, which creates a free bet on that selection (if your selection wins you make a profit, if it doesn't then you lose nothing).
There's no right or wrong answer really, other than ensuring the price is right in the first place, but I wouldn't use the cashout button as you'll never really get a favourable price, as convenient as it is.
Also keep an eye on dangerous match events that could send the price flying if you're betting late in the market.