Just google DOHC CB Cafe if you need inspiration. Welcome aboard.
My first bike was a CB750 as well, a '78 SOHC K model purchased when I was 22 years old. A couple pieces of advice? Well, start by getting the factory Honda service manual. The Haynes and other aftermarket manuals are pretty good, but there are some variances. You should also be able to find the factory manual for free download in PDF format. It is very handy to have printed and bound for reference, and makes it easy to tag important sections for quick ref.
Next piece: don't do anything (maintenance or otherwise) without understanding how and why you're doing it. A lot of mods you'll see and be inspired by have a net negative effect on performance and handling. Know the difference between which mods are truly upgrades and which are just for show. It's fine to like the way a bike looks, but if it risks the performance or safety of your ride, it ain't worth it.
Third: have fun with it. If it becomes frustrating, don't be afraid to ask questions. And don't get defensive or take it personally if some of the answers aren't what you want to hear. People have very strong opinions about what makes a good motorbike, especially one like yours which are both plentiful and popular. It would be wise to listen to most of them, some can be taken with a grain of salt.
