Excellent question. The great thing about youtube is that videos you post very quickly tend to show in Google search results, often quicker than the corresponding website would rank. Here are some tips:
- When posting videos paste your contact details/offer in the description and in the comment section
- When posting, ensure you copy paste a lot of the content in text form in the description so the video is easily findable when searched
- if you are in the US, you can use direct marketing to market the channel
- contact influencers and bloggers to link to you
- partner with other channels to advert vice-versa your channels
- paid ad
- link your channel with freebies and lead magnets

I would be delighted to better understand your situation and help you with it in a call