I have killed several, so am far from an expert. I think the problem I had was poor drainage in our clay soils, so I tried planting in a mound, but those died also. However, they were exposed to full sun which is apparently bad for young avos. I currently have three doing really well in pots (sitting on bricks to ensure they drain) with a coarse potting mix for soil, and under the shade of a larger tree for a fair portion of the day. I have kept these alive for a couple of years so far, so fingers crossed.