Simply put, if you don't have anyone that's financially dependent on you - life insurance probably isn't for you.
Life insurance exists to provide your dependents with a financial "cushion" that will see them through in the period after your death and for some time afterwards.
To help figure out how much cover you need the Consumers' Institute recommends that, as a minimum, life insurance should cover your debts, funeral expenses, full repayment of your mortgage and your family's immediate living costs.
In the real world, for most of us it will come down to what we can afford to pay - when this is the case, some cover is always better than none.
Once you have your figure, buying your policy should be straight forward.
My advice is to think carefully about what you really need. Don't be bullied into buying a product you dont need. And don't be pushed into buying more than you need. Keep it simple and make sure you understand what you're buying.