Many investors start their career by buying a rental condo, then another, and maybe a duplex or small house. Sooner or later they "hit the wall."
The "wall" is when your bank tells you they won't loan you any more money. Either you are too leveraged or you don't have have any down payment money and are trying to finance 100% of your purchase.
This is a common scenario and a very big problem. If you're in this boat, what are you going to do?
One way investors get around this is through joint venture partnerships. Quite simply, a joint venture is partnering with someone who has the money for a down payment and can also qualify for the mortgage. This person becomes a 50/50 partner with you on title and you pay them pack the down payment with interest when you sell the property.
Whatever path you choose to get over the wall, keep an open mind and a positive attitude. You might need a bit more determination, but you will succeed.