Because your business and target market is varied, I recommend picking an area of focus while you develop a process, evolve personal best practices, and learn. You have some good suggestions above. Pick on or two areas you can learn the most from, develop a plan, implement it, measure success and progress, and evaluate what's working, what's not working and where there's room for improvement. Adapt and go from there.
In terms of where to start, consider focusing on the product/services and customers you know best. Look to an area that already has established competitors so you can review what they've done well and no so well and learn from them.