One flower you might want to try is the lovely Vinca. It's an annual, gets about 12-18 inches high and comes in white, shades of pink and red. It's very easy to grow, very tolerant plant. You can toss these in amongst your daylillies to add green and TONS of blooms while your daylillies take hold. Vinca have a long bloom season without deadheading them-they will bloom all summer and into fall.
I find that blending perennials (your daylillies) with annuals gives the most extended blooming periods-and you can vary the type of annuals you plant to change the look! Another choice for you would be pansies for that early spring bloom, followed by your daylillies. Remember-daylillies need to be divided about every 3 years or they will start to decrease their blooming. And they are heavy feeders.
petunias (flowers all summer and very easy to grow)
snapdragons (flowers summer and fall)
phlox (annual and perennial types)
marigold (resistant to pests, blooms all summer)
peonies (great early summer blooms)
phlox (summer blooms-there are annual and perennial types)
delphinium (very easy to grow spring/early summer flowering-sporadic flowering all summer)
Overwatering is as bad as underwatering. Don't water small amounts daily either-that encourages shallow root development.
Good luck. Let us know how it goes!