Buck Converter MC34063AP
The link to the inductor data, that you provided, shows that the inductor has a series resistance of 6.8 Ohm and is rated for 180 mA only. If you wanted to draw 0.5 A from the output, the voltage drop across that resistor would be 3.4 V.
Furthermore the inductor would saturate.
I suggest you choose an inductor that can handle the output current (plus the ripple).

Grounding: unless you really know what you are doing, I highly recommend you to use a solid ground plane for the hole circuit and connect all ground connections as short as possible to it.
Generally the connections to the capacitors should be minimized. You can have longer connections to the inductor (but only the inductor - not the 0.33 Ohm sense resistor).

Good luck!