I have been on both ends of owner financing and it does have pros and cons. If you can get a loan through a bank it may be a bit safer and come with a lower interest rate. I also have a hard time saving money but I am very good at investing the money in real estate rather than just on myself. Buying property can be a forced investment or savings plan in a way because you have to make the payments and continue to gain equity in the property as you do. I would recommend doing a 5-10 year pay off if possible to gain equity faster and not have to worry about making those payments in 20 years.
Depending on many variables... property can loose value, hold value or gain value in the USA and most places. In general if you make a good buy and manage it well you will make money and it will also increase in value at the same time.
If you are buying through owner financing make sure to read the contract carefully. Some will allow you to lease the property to others or even finance the sale of it to someone else while others do not allow this. You do have that option but not with everyone.
If you buy a lot of land or any other type of property you usually have to hold it for a while to gain appreciation in value unless you do something to increase the value yourself (or if someone else develops the land next to it). It would be rare to find an owner that would finance the land for you at a price you could just put on the market and make a lot of money on in the near future. They would just put it on the market themselves and get more $ now rather than less later.
Why are you looking to invest in the USA? It may be easier to at least start in your home town and learn from that before investing in a country so far away.