Subject to's is NOT a rookie game. 1st if you aren't able to make good on your end of the deal you could mess up someone else's credit and is this case also cause that soldier to loss their VA loan benefits. Be careful with sub-to's.
If you want to do it right and not get sued, You need several disclosures with doing sub-to's so NO it's not just pull a contract out of you pocket. You need a contract that all parties understand that you a buying sub-to with out any guarantees. You need a power of attorney to contact the mortgage company and insurance company. You need to do a normal closing so there are no title issues and the correct deed is filed. There's plenty of courses out there that teach it. Books also. Educate yourself before doing. Sub-to's are a lot more indepth than wholesaling. You actually have to be responsible and have some built up cash for expenses.
Most sub-to gurus say rule of thumb is don't buy unless there's 20% equity in the home.
My advise is find someone in your local market (real estate clubs) that are doing sub-to and ask questions.
Good luck