Daisies are more of a problem in the lawn than the garden border. They can tolerate close mowing and still flower. They spread by seed so can colonise the lawn fairly quickly and become a nuisance. However they are easily to get rid of as they are susceptible to weedkillers and one application is usually enough to kill them.
The main ways to keep weeds under control is constant vigilance, never allowing the weed to flower or set seed.
If infestations are sparse then weed them out using a hand fork to help loosen the roots
Keeping the grass healthy and well fed will help to prevent daisies becoming established
Don’t cut the grass to short and keep the lawn well watered during dry spells
In the lawn either spray with a systemic weedkiller as a spot application or with a selective weedkiller as part as a weed-and-feed programme. Some systemic weedkillers may kill the surrounding grass but a weed stick, such as Elliott's Touchweeder which is brushed on to the weeds leaves won’t harm the grass