I will recommend you to apply this through Linkedin (mindset and tools fit better) but you can go for other platforms as well.
Here is the 4 step strategy for business development on linkedin:
Step 1: Expand Potential Client Pool
If you have a service or a product you should know who your potential client is. Linkedin search is super capable to find you 100s of similar profiles with similar job titles and location filters. The best part is when your audience grows your potential reach grows even more.
Step 2: Prepare Authentic Personal Messages (Copy)
You have probably received a number of spammy messages on your email or through social.
If you want to reach and work with more people, be real, prepare an authentic copy and personalise it a little for everyone.
Make people feel they can trust you on the long term, be that person and show that you can solve a problem, cure a pain, be helpful.
Step 3: Systematic Reach for Systematic Return
Add people daily from select job titles or places and connect with them through DM.
If you provide value, if people fit your client profile and if your copy is good, you will end up with new clients every day, no joke.
Do this systematically, add 20 people and send 10 messages every day.
Step 4: Fine Tune & 10X
Now you have a system, not a perfect one but you have some returns.
To increase the returns, polish your copy and value with the feedback from the on going campaign. See how people react to your messages and make A-B tests with little changes.
Collect data and iterate your system until you have 20% return rate.
Then 10X it, if you wish to see your potential or really scale your business, 10X your fine tuned messages.
It sounds easy but it takes a while to get into flow. If you wish to have a cheatsheet with further details and checklist, download it free from here.
I have consulted and fine tuned 10s of campaigns for friends and clients, they have achieved more than their expectations with this strategy, hope it helps you too.