Hello Davenport,
Firstly, any layout is a good layout !, so enjoy the experience, learning & fun (plus occasional frustration at times). From my own experience, I put far too much in to my first layout, learnt from that over ambition, which takes me to my second observation, 'less is more" - consider perhaps one less main line. Next consider how many sidings do you need, perhaps just one set rather than the two showing ?. Also consider the space remaining for scenics, and what type of scenic settings are you going for ? - Metcalfe card builds for example are relatively inexpensive, enjoyable to build, but even so, take up quite an amount of space, you will also need roads in/out for the freight trucks, an open yard for container storage and loading equipment/vehicles etc. Hope these few observations are of some help.
You are off to a great start - enjoy the adventure.