[homofaber]

Best thing you can do is start with small.projects (as you did) and growing incrementaly. During that time you will learn how different circuits work together and problems with more complicated circuits boards will need to be solved one at a time.

Contacting local hardware groups can help.

Basically, same as programing books can take you to some point, but when your project outgrows and become complicated with multiple rarely combinated libraries... you are on your own and, hopefully, you will be ready to take that bite.

Also, being more concrete in explaining your needs could get you more help.