Youtube - make channel look more professional; Thumbnails + Edit

Main Aim – to make the channel look more professional.

Our mentoring programme is in its infancy but we have been building up YT videos for about 7-8 months now.
Primarily we help Martial arts School owners improve their business (increased cash flow and profits), however we also help some sports club owners i.e. dance, gymnastics, achieve the same goals. We also have a business owner who we are doing great things for too.
We now want to make the channel look better.
When any of our leads or prospective leads land on the channel we want them to have a good/excellent first impression.

Objectives –
1. To put thumbnails on at least 30 videos
2. To have a subscribe + like CTA on each of the above 30 videos (maybe at the start and then at the end?)
We have only chosen 30 videos because we do not know how much it will cost per TN etc. If the price is reasonable then we would look to do more.

Further Improvements –
If you have any other suggestions that would make the channel look more professional, then please advise. We do not have an ‘blank cheque book’ but would like to hear what else can be done to optimise the channel.

Likewise, if you are competent at driving relevant traffic to the channel please also advise. We are obviously not looking to earn money from the channel, the main aim is to drive leads or potential leads to our website. From there they may decide to enrol into our mentoring programme.

Channel Title = Dervish Dervish