Nice to see you taking steps to improve your network, @Wei Huang!  

However, I read through the VA Lenders Handbook and found the section where it talks about Joint Loans.

There is a whole science to improving your score.

When I discovered that my credit was less than what it needs to be to do any kind of real estate investing, I started intensive researching for ways that I could improve my credit rating.

It is also possible that the "improvements" (ie the building) isn't accounted for.

How are you going to finance and were will you get the money for improvements?  

They will make the monthly payments, take care of repairs and improvements inside and out at their expense.

@Mark HoDo a joint venture w the sellerYou want to offer the seller a joint venture agreement and buy it on subject to and get titleYou give a note for their equity in the JV agreement you agreed to pay after note in 3 to 6 monthsYou have title and then you sell w an agent pay the costs to sell with the agent pay the note off and hopefully you have a good JV fee as profit

I may look at the 201k loan - as this would enable me to make repairs and possibly improvements that negate some of the risk of owning an older property. 

The purpose is to buy with little money down and also finance the improvements.