What is the best way to start? Small
10 hens is about right so you are part way there already. 1 cock will be enough.
In the end, it is the same for everyone: you have some hens and a rooster, they breed.... your flock grows.
Now in between all that, there are a great many details.
Coop size is generally given as 4 sq ft/bird of floor space. That is sufficient if they are outside most of the time - as they should be. The coop is for roosting and nesting, mainly.
Outside space should be bigger than you think. 50-100 sq feet per bird.
The exterior living environment you create for your flock is where you want to sink the majority of your resources.
I am not a big fan of rampant "free ranging," as most people hardly understand the true nature of the practice.
I suggest range managment as part of paddock rearing, instead, where the birds are treated similar to other livestock - living in a controlled environment. With 10-15 birds this is fairly well managed without a lot of cost or effort.
Just use common sense, and avoid overcrowding. That is RULE NUMBER ONE. Overcrowding is the largest problem people have... and they often dont know it.
Along with this, keep the birds well fed, give them fresh water, keep them very clean and free of mud and dampness.
Do these things and you will go a long way to a great start.