;D..as Tony said..
I would like to add to that though...it is all down to your ground/growing conditions and trying to make it better so that all those seeds you are planning to sow will germinate in first place.
Raised beds ,,even just slightly raised are ideal as seed beds..they warm up/stay warm and has better drainage..nothing worst than having seeds and seedlings sitting in wet soil.
I don't have much use for 'seedbed' in ground..you always get too many casualties due to that odd slug or bird..or bad weather.. ::)..but when ever I've made one...I use spent compost, loads of grit and sand and trying to get it mixed together with top few inches of soil..watered in allowing the soil settle for few days/week before sowing...and then making a net cover or using coldframe over giving best possible conditions for germination.
Fertilizers are not needed as 'rich' soil does more harm than good, thus using 'spent compost'.
If I were to make seedbed for something shrubby or trees..I would make the mixture more 'wooland like'..using leafmould rather than compost...'horses for courses' ;)