Beginner's Advice

Hi there! First post round here, so greetings to all.

I recently caught the bug after moving into my own house late last year. The garden when we moved in was pretty much bear and overgrown apart from a lovely Camelia and an over-grown butterfly bush.

Anyhoo, we started off randomly choosing a few shrubs to form the backbone of a garden, more for something to do than with any realy intention to make the garden lovely, or take it up as a hobby. Then we got a few geranium plug plants which did really well in pots down the side of the house, a honeysuckle which again is doing really well, two fatsias, three cordylines, two bamboos, two palms, one of which was brought with my partner when we moved, a pineapple broom (which doesn't seem to be doing very well at all), a russian vine, and labernum tree, and a virgina creeper. Some of these were bought after we had decided to put a little thought into the design of the garden.

Now we are looking to next year, and think then it will be time to start on putting in the perennials along with some annuals which can be changed every year to give some variation in schemes. What I'm looking for is some advice on easy, but interesting things to grow from seed (bearing in mind that my propogation equipment consists of windowcills!). I'm thinking of seeds due to cost implications. I'll be buying some plants directly form the garden centres (I've got my eye on echinacea and understand these can be tricky to grow from seed), and I must have a Chocolate cosmos, and one of the more interesting other cosmos available. We tried to grow cosmos form seed earlier this year, but they ended up too leggy. Any idea why that happened? Not that it made much difference cos the dog decided to trample on them all save one when it came to planting them out!

We have quite a clay soil, which I have tried to improve by digging in lots of compost but it still seems to hold quite a bit of moisture for a long time, expecially after the weather we have been having lately. One side of the garden is in full sun for perhaps half the day, while the other is in shade all of the time, so these might be points to bear in mind.

I'm going through the seeds catalogues for things that catch my eye, but I am aware that the plants I like may not be suitable for my garden or position

Any help anyone could affer would be great