For all achievements that are to die (500 deaths in total) there is a simple method, you can knock this out of the way right away or you can do this last (Recommend this one AFTER the Kilometers achievements).
There is a sure method of ways go getting this... They all lead to 1 thing: putting a bed down next to the area you are going to die. You can stack woodframes up really high, put your bed down up high and just keep jumping off, anything that can kill you just put your bed next to if possible and you will get them in no time.
My favorite and most easiest method to get this is putting a bedroll out in the radiation zone (at the edge of the map) and all you have to do is keep hitting the
button until you hit 500 deaths for the final death achievement.
Do note, if you plan on swapping kills with a buddy (if you can kill the same person 2500 times) don't waste your time going for the deaths because you will get them giving your buddy kills: