Here are some thoughts:
1. Keyword in the title: I use the formula of 1 1/2 times in the title. (example: Charlotte Plumber | Best Plumber)
2. Keyword in the description. You can take liberty with YT in keyword density... keep it higher than you would a regular website.
3. Related keywords. Put in plenty of related keywords to get your video to rank for as many variations/longtails as possible over time. I simply list all of the related keywords at the bottom of my description.
4. If its geo-targeted keyword, make sure you geo-tag the video to the location you want to rank for.
5. When you upload the vid file to YT, make sure the file is named exactly your main keyword.
6. Open an email account and use your keyword in the email address. Use that address to sign up to YT account.
7. Build backlinks, if needed.
8. Buy some cheap views.
There are a few other things you can do, but the first 6 steps should EASILY get any low competition keyword on the first page within a short period. Add 7 & 8 if you need to.
As I say, there are a few other things, but this should be good to get you started!!!