Homemade dynamo and alternator
Looking at websites of people who have much experience in this area is an excellent start. The few example sites I mention below vary in how much theory and alternator design they offer but some are reasonably good. I have not looked at any of them in any detail for some while, but some will get into flux, magnet sizes versus field depth, core materials / laminations / "ironless", axial and radial flux alternators, air gaps, saturation, phases, cut in speeds, ... . Many sites major on the mechanical aspects but there is enough of the theory on this sort of site to get you going. After that there are any number of academic papers available - many for $ but some free. 

An excellent cross section of ideas, practice and theory can be found at  Hugh Piggot's Scoraig Wind site. And here

This gives you an idea of the sort of things he deals with

Also good is The Back Shed 

You are probably thinking of a HAWT as per Piggot's products, but VAWTs  are worth a look for various reasons.

A good performing not too hard to built is the "Lenz"  design. 

An example Lenz VAWT - do not be fooled by the appearance. Also do not believe the categorisation of this as a drag turbine. It's a hybrid with TSRs of over 2 in some situations.



The term "axial flux" is an excellent one for finding related articles as while it is not limited solely to this field it is the major area where the term is used. The web search "axial flux" design produces many useful leads.

As elsewhere - quality varies but much is useful. eg

Thesis 2005 DESIGN OF AXIAL-FLUX PERMANENT-MAGNET
LOW-SPEED MACHINES AND PERFORMANCE
COMPARISON BETWEEN RADIAL-FLUX AND
AXIAL-FLUX MACHINES  - and I get to learn a new place name (from Lappeenranta
University of Technology, Lappeenranta, Finland)

IEEE. For $. Abstract. Just reading the abstracts shows you what you may wish to know. Electromagnetic design of axial-flux permanent magnet machines

And another. Design and Analysis of 42-V Coreless Axial-Flux Permanent-Magnet Generators for Automotive Applications

Even a design "axial flux" image search looks like a gold-mine (or a Barium Strontium Titanate ....?)



Searching Youtube for "axial flux" and "radial flux alternator" produces many leads and you can soon decide what to follow from there. Information provided is variable and "uneven" and many major on the practical rather than theoretical, but much can be found that is good. 

A word of advice  - anything that uses the words "overunity", "free energy", "... magnets ..." as a key title should, at most, probably be put aside for another occasion. Almost all such sites//articles are provided by people who either do not understand what you are trying to learn about or who arecon-men (there do not seem to be too many con-women in this field). 

This will give you some ideas