This is a good idea, if you know how to operate most effectively. Pay attention most not just to the one activity you like, but concentrate also on those that bring you best results. Learn to deligate and hire professionals to the activities you'd like to be covered by someone else. You as a CEO should concentrate rather on gaiining more contacts and customers, working on strategies for your projects rather then getting stuck in operations management.

Basically you want to use both-inbound and outbound marketing.
Start small, if you already had your customers, for example from the freelance websites and you still keep in touch, you should ask for the feedback.
You can start with a landing page with clear description of the services you provide, and the reviews from your previous customers. You can make case studies for each of them to describe the complexity of the following tasks and how you solved and acheived your results.
The easiest way could be facebook ads, it is easy to make few targeted campaigns there and test which work best for your purposes.
Another way to claim your professionalism: creating your personal brand on social media and continuosly advice and create lead-magnet content, that will engage people to trust you as an expert.
And 3rd but not least: As you start your company, work on vision, mission and objectives, understand your ideal customer and the price that you are selling your services. And go for it: make a list f the companies that can be your relevant customers and reach their decision makers through Linkedin/their website and other forms of communication.

Will be glad to shortly give you the advice on the best leadgen tactics and discuss the materials that you already have starting your company

To answer your question, first of all remind to yourself why you want to do that in that niche. You may have such a conclusion about crowded business because you are already there and all you see-your competitors.
First identify how you are different and what value you can bring to your customers, why they should chose you before your competitors. 100% of buyings are emotional decisions, what emotions your product or service brings up? How you are representing those emotional patterns to your potential customers?
There are still many businesses that just making things done. And if you master making things done even a little better than any of the mediocre competitors than you still have more chance.
It is 50/50 between your state of mind and consistency.

Good luck on your businesses!

Start with your personal objectives, what you want to achieve and accomplish through your business?
All in all starategy starts with VMOSA: Vision Mission Objectives Strategy Action plan
1. What you want to achieve?
Strategy - is the art of war. After understanding your objectives, find out what you want to defeat, is it a size of the market? Is it a certain competitor? What have they done to get to that point? How much time you are willing to spend to achieve this goal? Is it money vs time in your case? What are you able to neglect to get to that point?

Will be glad to have a short call with you during the week while I am testing out this service for free:)

Good luck on your path!

These are some wonderful answers here.
0. I would advise you to find mentors in the field you are working at. This is not obligative, but very helpful.
1. As any business searching for clients first objectify who are your ideal clients, what are their problems, what is your main focus that you are tatally great at and passionate to keep improving.
2. Linkedin, emails, yellowpages, directories, friends, recommendations of your surroundings. Everything works to find your first clients. As well as here you might start almost with lower prices to build up your portfolio and recommendations list.
3. Make sure your social profiles represent you as the professional, build your personal brand online. Great sources for that: facebook, personal blog, linkedin, youtube, anything that can be a social proof of who you are. People are buying from people.
4. Make sure all of your paperworks are proper for your country and your state, be open and clear with your business to build trust through your actions.

I will be glad to shortly speak to you and probably be helpful for your start. Please ping me, pretty sure we can exchange some experience:)
Good luck on your path!