Poolgoddess, most likely you won't get it all right the first year, so try to relax. Some plants will grow taller, or wider, or slower than you expect or the packets say. In fact I am still working on design in garden beds that are 8 years old now. Fairly well ordered and the bones are in place, but plants die, are eaten by voles, get too big, decline, sun patterns change as trees and shrubs grow, etc. so I am always moving things around and adding new things.

I keep an excel sow chart every year, that includes the species/cultivar, date sown, # seeds, date sprouted, etc. In the first year I included sun preference, height, and moisture preference. I used the "wetland indicator" from the USDA plants database, which consists of a range between wetland, facultative, and upland plants (or you could wet-mesic-dry). But after I became more familiar with the plants I dropped those columns from the chart and added notes instead.

I haven't ever tilled, just hand dig the gardens. But the first year I would mix in compost and maybe leaves etc. using the shovel or tiller. Once the soil has a good texture, you don't need to turn it every year. After that you can topdress with compost or scratch in some fertilizer each year. Flowers need some nutrients, but generally aren't as nutrient intensive as veggies. Organic matter will attract worms which will also fertliize the soil.

But some flowers like it lean - fertilizer makes their growth floppy or too much nitrogen can encourage foliage growth over flowers!

The one thing I'm careful to note besides what's already been mentioned, is whether a perennial plant makes a taproot or is otherwise hard to transplant once settled. I'm more careful about placement of those plants. Anything else is fair game to "plunk and run" wherever I see a spot at transplant time. I figure, if I decide later it's in the wrong spot, I'll move it.

Annuals are temporary anyway. If I decide I don't like where they are this year I'll do it differently next year. For example, last year's larkspur was shorter than I expected, and planted in the back of the bed where it hid behind everything else. This year I'm planting some in front.

Great advice terrene and edie, although be careful what you wish for when it comes to larkspur. Mine was in a mixed seed pack a few years back and it grows tall and plentiful every year now -- it reseeds like crazy, and since it's outside one of my veggie gardens I'm pulling it like a weed from inside the fence as well. It is pretty when it blooms against the fence, though.

Caryltoo I had the same problem with HH. They reseeded and came up everywhere in the garden. Those little suckers are impossible to pull by hand.

Poolgoddess, how is the sowing coming along?

They are all sowed, but it snowed again, so probably not till next weekend before I see sprouts. But spring will come! I did:
Nasturtium
Creeping Thyme
2 pots marigolds
snapdragons
Daisies-shasta and african
2 money plants
forgetmenots
pansy
coleus
columbine
hollyhock
dianthus
sweet william (biennial)
2 pots alyssum
2 pots petunias

some are probably too early, but I have more seeds of the multiples I did sow, so no harm no foul, lol

You will be good.