When does pushing genealogical research into the past become more than an interest and become a full-time job? About the time you have to learn a new language or handwriting system? I have discussed this topic from time to time in the past, but there is always more to say. Although it is probably subjective, every 100 years into the past adds a measurable degree of difficulty. As I pointed out on my last post, printed books in Europe date from the middle of the 15th Century. But if you are doing genealogical research, the reality of the existing records mandates recourse to handwritten records, in most cases, much later than the mid-1400s.
Besides people with notoriously bad handwriting, going back in time adds challenges from the changes in styles. There is no substitute for actually trying to decipher the old documents. Fortunately, there is an abundance of resources for learning about old handwriting. I would start with the British National Archives. They have a practical online tutorial for reading old handwriting. The study of old handwriting is called paleography or palaeography in England. The online course was developed in partnership with the School of Library, Archive and Information Studies, University College, London. Of course, this particular course is limited to English records, but there are a lot of other resources available. A lot of what is online is simple drivel and of no real help, but like the The National Archives site, there are some notable exceptions.
OK, now if you really want to know about handwriting, you go to FamilySearch.org and click on the Learn tab at the top of the page. There is a listing for Research Courses. FamilySearch has courses in Dutch, English, French, German, Italian, Latin, Polish, Portuguese, Russian, Scandanvian Gothic and Spanish. Most of the languages are broken down into a series of 1/2 hour classes. The courses include PDF handouts and handwriting practice sheets. I am certain that there is nothing else this extensive online on this subject.
If you want practice reading old documents, there are plenty of them on FamilySearch.org's Historical Record Collections. Just go to the country and time period you are studying and open any of the images. Chances are the documents will be right at the level you are studying.