Sail close to the wind
Acting just within the limits of what is legal / acceptable
Skate on thin ice
Do something that could cause you a lot of trouble
Watch your step
You must be careful
On the safe side
Don't take risks / To be careful and cautious
Play with fire
Someone is doing something that will result in them being harmed (physically or emotionally)
to be wrapped in cotton wool
keep yourself / someone very safe
Live dangerously
To lead a lifestyle characterised by taking risks
Throw caution to the wind
You start taking risks and stop worrying about the dangers involved
Dangerous ground
A topic or opinion that is likely to upset or offend others
Risk life and limb
risk your life
Safe as houses
Completely safe
Stick your neck out
Be willing to take a risk - often for other people
Take a gamble
taking a risk / don't have much information about something