I don't know much about home improvement, but this one's pretty set as is besides the deck/windows. It was built in 1908, but has been remodeled, new roof, furnace, electrical all from 2012-2013. Remodeled hardwood floors and kitchen, so altough old, they did a good job of modernizing it and doing a lot of the work recently. I'll learn the things as I can, and if I decide to go with a friend building the deck, I'll be there for every minute of it. But a deck is such a random thing that you replace/repair only every 10 years or so, so if I have to go pro and don't get anything out of it, oh well I guess. Windows I think should be done professionally. I actually didn't have any friends comfortable with doing windows. But I'll definitely learn/fix things as they come and as I can, but I don't have the background so will have to do the research.
I bought a 15 month home warranty for ~$400. It covers quite a bit, any appliances, furnace, electric, plumbing, roof, etc... So if something went wrong, I pay $45 to have someone come out, then I pay essentially a 20% co pay to have whatever needs fixing, fixed. I'm going to have to put more money into this in these types of ways because I don't have the background, but even with having to hire/warranty some things, it made sense financially.