Different strokes for different folks. Shallowest I fish is around 25m but generally around 60m etc. The only thing I'd add is to approach the area you want to anchor and just let the boat drift back a while, then approach the spot and go past it, general rule of thumb is at least the depth you are in - this can increase if there is wind etc then drop your anchor. For example in 30m of water I would go past at least 30m but often 40m if a bit of wind.
Doing it this way you are approaching the anchor spot from the direction your boat will hang and you won't wrap your anchor chain around a bommie, hopefully.