Starting with the motor... but how?

Hi guys,
About a year ago I purchased a 16 foot Tuffy with a Mariner outboard and kicker on it. Well, I'm at a point where I completely avoided working on the project this entire year because I have no idea where to begin. I was hoping to get a bit of guidance.

I'd like to start with the motor, I have a key but I have never hooked up the gas, or a battery or tried to start it up. I'd like to go about doing that but I'm not even sure where to begin. I'll post a link to a brief video I tossed up last year, but seriously... where do I even begin with this??

Thanks for any and all input!

https://youtu.be/JKRYkmaui9U

First thing,get two manuals, http://www.marineengine.com/manuals/seloc/mariner.html ,you have a Mercury Mariner,60HP,built by Mercury,and, If I'm seeing right,a Yamaha Mariner,built by Yamaha for Mercury,painted the Mariner colours and sold as such.It will have Made in Japan on a plate riveted to the bracket.The wrap around on the 60HP says 70s' early '80s'. Post the engine numbers for a more accurate year of Manufacture.
Hook nothing up yet.Pull plugs and turn the flywheel by hand,if they move spray some WD40 or similar into the cyls.Then hook up a battery and do a compression test,the oil will distort the numbers a bit but nothing serious.110 psi or thereabouts on all cys would be a good starting point.
They both look pretty tidy so good luck.Oh you are missing the front plate from the 60HP

Hey there! Thank you for the helpful reply! I will go and check some of this stuff out, I'll actually plan to tape that here in the coming week. There is so much to do on this project I feel like the only way to walk through it all will be to log my "progress"... and I use that term loosely. Thanks again!!