I currently run a B2C online service. I'm looking to pivot to B2B as a way of growing our business.
I'm a very practical and tactical marketer so in this answer I will give you a series of steps to run through. You will need to run through them all several times - for example if you do 1,2,3 and it's not working, go back to 1 and start again, improving each time.
You will need to be very self-critical in order to improve and if you have not got experience in B2B I strongly recommend you find a mentor or coach who can be objective and help shortcut the number of iterations.
First - write out the revised offer as it would apply to a B2B situation. Make this a one-page print and pdf brochure.
Second - approach people you already know and who could buy the service and ask them to appraise the document and give you honest feedback. You can find these people on Linked In or via the local chamber of commerce. Get the feedback face to face if possible and / or by phone. DO NOT use email. You want to be there in person to ask supplementary questions such as "why did you say that?" to clarify your understanding.
Third - try to push a sale or two from one of your market testing interviews. Be prepared to offer a money back guarantee or a discount with the option to name them as a client as the quid-pro-quo.
Fourth - You should now have a sense of which TYPE of B2B firm could buy the service. So go and buy a mailing list of similar businesses in your local area. Approach them all and repeat - raising the price, reducing the guarantee as you get more focused onto your sweet spot.
Fifth - as you approach more, try to refine the offer and price if sales are not forthcoming. This will allow adaptation to refine the offer to suit the market. And also gradually withdraw from the face to face and phone and pull back to web (low cost) sales. You may still need telephone follow up. Experiment with having a colleague do this calling rather than yourself as you further move to lower cost marketing tools.
Sixth - re-invest any profits into improving the marketing method and collateral.
That should give you a methodology. Now you will need very strong copywriting, CRM and sales skills. Buy or hire these for your support team.
Good luck and happy to help further.