novice gardener seeking advice!

Hello!

I am looking for some advice as to what I should do with my garden. I moved into my house over a year ago and at the front there was a badly overgrown area, I have since cleared it and re-edged it so it is somewhat of a teardrop shape.

I have attached a couple of pictures and my thoughts so far are:

1. I would like to have a tree in the lawn around the area where the teardrop narrows but I don't know what would be appropriate. Any suggestions?

2. Within the teardrop shape I was thinking of a weeping cherry blossom and then other things so that it is graduated down to the narrowest part. Again any suggestions as to what I should plant?

3. In my mind I picture the planting to be a spiral with the tree being the highest point in the garden and then gradually getting smaller in the teardrop. Hope that makes sense!

The ground isn't fantastic as the estate was build on a brownfield site and was littered with reminants of the old building but I have tried to clear as much of that as possible. Is there anything I should do or add to the soil to improve it?

Any suggestions, help and advice would me much appreciated.

Thanks

L