What should I do: Cold Call or Long-Term Building Trust Investment?

Start by posting youtube videos, making blogs, instagram and facebook, since these apparently are the methods you plan on proposing to your clients. In addition, consider promoting your content (videos, blogs, posts, articles, etc) to online/offline publications which are already targeting your prospective demographics. Cold calling can be very powerful for quickly crashing through obscurity, but it requires leveraging a strong online presence.

I'm always going to be in favor of the long term trust building movement. That has always resonated with me. I think it's because I put myself in the buyer position and ask myself if I would buy under these circumstances.

Establishing your social media presence and making QUALITY posts are important for gaining trust of your potential customers. One tweak to your plan I would suggest is to post much more often than once a week. The recommended number of DAILY IG posts is ~3. On top of that, you need to be engaging with people in your niche - liking and commenting on their posts.

It will be a challenge for you to do Youtube vides, IG, blogs, FB frequently, but that's the game we play. Personally, I focus on one platform at a time, but will share that post on my other platforms simultaneously. Again, it can get time consuming keeping up with the comments and questions from followers on all platforms. However, this is how you build a brand and a dedicated following.

Cold calling works as well, but I think most people will agree that the skills required to successfully cold call takes a lot longer to master than marketing online or building a social media brand.

What type of marketing are you going to be doing for clients?

Business owners like to build trust, especially small business owners that have a lot of time invested in whatever their business is. If you can show and prove the value that you can provide for them you will gain clients. I think keeping up with all of the platforms mentioned may be difficult but as you go along you will see what works best for you.