I think it all down to ones preference and I'm not going to tell you how to suck eggs but instead I will tell how we do our raised beds we make our raised beds aprox 12 inches high 6ft long we dig over the ground fill the ones we need to grow brassicas with half well rotted manure and half compost to top of
some veg we don't need manure like parsnips so we dig over the bed and fill it with compost usually its spent compost from our tomato or other things when we empty the greenhouse and pots sometimes if we haven't enough used compost we buy whatever's compost is on offer
also I made brackets to fit the raised beds for environment netting on every raised bed obviously I don't know what your soil is if heavy or light soil I ended up making twenty raised beds out of re-claimed decking I treated all the timber before making the raised beds but I have found raised beds to be much easier than open ground sowings and planting the only open ground plantings we do now are runner beans main crop potatoes and some broad beans and peas the early potatoes go in the raised beds like all other veg
I'm going for a salad raised bed this season if it stops raining for a couple of days
i also built a fruit cage more or less on the same plan as my raised beds with boards round the cage and filled with manure round the bushes
i have to say making the raised beds did take me a week to make and another week to install them down the allotments but then being retired time was not an issue hope this reply helps you and good luck with the raised beds