While it might sound counterintuitive to let the bad bugs stay, a few here and there won’t do your plants any harm. Resist the urge to kill aphids as soon as you spot them on your plants.
If you must use any kind of chemical control, opt for insecticidal soap or horticultural oils, which do less damage to lady beetles.
They prefer small flowers, flat open petals, and umbellifers (umbrella- or disc-shaped flowers) that they can land on and crawl over easily.
You can influence ladybirds to stay in the area by providing a safe location for them to overwinter.
An example of this is an “insect hotel” or bug hotel, set up in an area that gets southern exposure for the best warmth.