I was not able to find any good crochet patterns for the kind of sandals I wanted to make. After lots of research on the net, I decided to make my own. I even remembered to write down what I did (for once). This is my first time attempting to write a pattern for others to use, and it is untested. Please let me know if you have questions. This pattern has very few ends to finish, and works up in a jiffy.
These will fit a newborn. They worked up to a length of 3.25" or 8 cm. I've always found that the standard 3.5" or 9 cm are really too big for newborns, so I made those a touch smaller. You can use a larger hook and thicker yarn for larger feet.
This is written in American crochet.
Hook: Size G - 4.0mm
Yarn: Small amount of lavender and small amount of white, rated for hook size G.
Gauge: Not critical as the ties allow for some adjustments.
Stitches used:
Chain stitch.
Slip stich.
Single crochet (sc).
Double crochet (dc).
Shell stitch (2 double crochets, 1 chain, 2 double crochets in same stitch)
These will fit a newborn. They worked up to a length of 3.25" or 8 cm. I've always found that the standard 3.5" or 9 cm are really too big for newborns, so I made those a touch smaller. You can use a larger hook and thicker yarn for larger feet.
This is written in American crochet.
Hook: Size G - 4.0mm
Yarn: Small amount of lavender and small amount of white, rated for hook size G.
Gauge: Not critical as the ties allow for some adjustments.
Stitches used:
Chain stitch.
Slip stich.
Single crochet (sc).
Double crochet (dc).
Shell stitch (2 double crochets, 1 chain, 2 double crochets in same stitch)

Sorry about the bad picture.
Sole:
Chain 12.
Row 1 -
Double crochet in 3rd stitch and in next 7 stitches, for a total of 8 dcs.
6 dcs in last stitch.
7 dcs on other side of the chain.
3 dcs in last stitch.
Join with a slip stitch.
Row 2 -
Chain 2. Do not turn.
2 dcs in next stitch.
1 dc in next 9 stitches.
*2 dcs in next stitch* Repeat from * three times..
1 dc in next 9 stitches.
3 dcs in next stitch.
2 dcs in next stitch.
Join with a slip stitch.
Sole is about 3.25" or 8cm long.
Do not fasten off.

Heel detail.
Back heel:
Chain 5.
Join in 4th stitch across the width of the sole with a slip stitch.
Chain 1.
Make one shell stitch in the center of chain 5.
sc in last stitch of chain 5.
Heel completed.
Do not fasten off.
Slip stitch in next 6 stitches along the edge of the sole.
Back heel:
Chain 5.
Join in 4th stitch across the width of the sole with a slip stitch.
Chain 1.
Make one shell stitch in the center of chain 5.
sc in last stitch of chain 5.
Heel completed.
Do not fasten off.
Slip stitch in next 6 stitches along the edge of the sole.

Front top (toes part):
Chain 12.
Row 1 -
Anchor across sole with slip stitch. You should anchor 6 stitches from the heel.
Chain 2.
1 dc in each chain 12 stitches.
Anchor to sole with a slip stitch.
Chain 2.
Turn.
Row 2 -
*dc in next stitch, chain 1, dc in next stitch* three times.
Chain 2.
dc in last stitch.
Chain 3, turn.
dc in center.
Chain 3.
sc in last stitch.
Finish, leaving a tail for sewing.
Sew toe part to sole.
Chain 12.
Row 1 -
Anchor across sole with slip stitch. You should anchor 6 stitches from the heel.
Chain 2.
1 dc in each chain 12 stitches.
Anchor to sole with a slip stitch.
Chain 2.
Turn.
Row 2 -
*dc in next stitch, chain 1, dc in next stitch* three times.
Chain 2.
dc in last stitch.
Chain 3, turn.
dc in center.
Chain 3.
sc in last stitch.
Finish, leaving a tail for sewing.
Sew toe part to sole.

Either thread a ribbon or make a chain for laces.
Finish ends.
Make a second sandal.
You can embellish or leave as is.
Finish ends.
Make a second sandal.
You can embellish or leave as is.
Additional photos below.
Pair it with a little matching dress.