Getting over my fear of cutting wood!

Took me a while to go buy plywood and 2X4's for the framing and new subfloor- I have to admit it is daunting to go to a lumber yard full of burly men and act like you know what you are doing.  However, I quickly got over that insecurity, and successfully went to buy my lumber...  
And's not cheap! Wowza.   I'll keep my receipts and see what this whole project costs me...but whatever it is won't matter if I succeed in this new adventure!!

I first wanted to put some wood in the frame to support the seams of the new plywood going in.  
I cut the 2X4's to the needed sizes, and screwed them into both the existing 2X4's as well as the metal frame.  Not too hard- just took some thinking as to how best to do it. 
Of course- Mobiltec's videos continue to help me immensely.  
I refer to them again and again to make sure what I am doing is correct. 
Thanks Larry !! 
I also painted the whole frame- first sanding and then using rust inhibitor spray paint for the metal frame, and covering the whole thing with asphalt fence post paint.  Messy...but looks good.
The frame is in good shape for being 52 years old- and I hope it lasts another 50 years! 
Now for the floor...
Measuring and cutting an expensive piece of plywood is another daunting task.  What if I screw up??Can't say I have much experience with measuring to the 16th inch on a tape measure! 
'Measure Twice, Cut Once' in the mantra I have heard- but I think mine is now 
'Measure 10 times, Cut Once With Great Fear" ! ha ha ha

Because I did not remove the cabinets- I had to cut the wood to fit around them- 
which led to the measuring woes. 
However, I finally just said "F- it", drew my lines, and got to cutting with the circular saw. 
I was glad I had some experience with using a circular saw- 
as I cut straight on my lines with little effort.  
The final test...does it fit correctly??
I am happy to report that it fit like a glove!!  Yahooooo!!!
One more piece in the front, and I am done that part of the flooring. 
Of course, I'll need to do it in the back also, as the floors are a mess there too.
However, I now have more confidence with what I am doing-
so it should not be as hard :)