I have the Up-N-Out dinghy ladder (https://up-n-out.com/dinghy-ladders/).
When properly tied to the dinghy, it won't kick under the dinghy and doesn't require much arm strength to board.

If you don't have a ladder, I find it easiest to board at the side of the dinghy nearer the stern where the top of the tubes are closest to the waterline. Keep your swim fins ON then kick upwards and pull yourself up simultaneously.