Digging a hole is a problem. They need a bed with good drainage. If the hole in the clay soil holds water, it will hold water no matter what kind of soil you put in it. The only way to assure good drainage is to prepared a well drained bed. When drainage is poor, this means a raised bed. Azaleas have very shallow roots so the bed need only be about 6 to 10 inches above grade to provide good drainage.

Next, to assure low maintenance, you must provide the ultimate low-maintenance elixir: mulch. Mulch does many thing, among them:

1) prevents weeds from gowing,
2) conserves moisture
3) keeps the roots cool

When mulching you can use about 2 inches of pine straw, oak leaves, pink bark, etc. This step is very important.

Azaleas don't respond too well to fertilizer when under the stress of being just planted. You don't normally need to fertilize the first year or two since the nursery did this when they forced the plant for sale.

Here is a link that might be useful: How to grow azaleas and their problems.