I've been through this myself with every business I have started and there's no easy answer to this - you just do.

The usual path is you'll go through a hopefully-not-too-long period where you try things and they kind-of work... and then one day it just does. It's not an overnight event - it's the culmination of that long process of trying different things.

As others have suggested a support network can help if they pull you up. But stay really, really far away from people who drag you down or try to discourage you from your ventures.

It also helps if you are currently kicking *ss in another area of your life - some sport, the gym, some other hobby you have. That will remind you that you are capable of doing amazing things and that your business is no different.

Your harshest critic is going to be yourself and that's where the self-doubt comes from. You will see others around you succeeding and doing amazing things and wonder why you are not doing the same. But you can. Everyone goes through the ups and downs, some just hide it better than others.

Talk to other entrepreneurs and business owners. Hear from them the challenges they have gone through, and recognise that in some areas you know more and have done more than them, and in others, fair enough, you have a bit to learn.