@Qwesi McCray, (and whoever else might this helpful):
I've used @Joe Villeneuve's 1st listed strategy for buy&hold investing since ~2009. I've never considered it "no money down" investing though. I consider it investing with "borrowed money". It's "non-lienable debt" as Joe calls it, but I pay back my debts no matter what, so I will take the losses if something goes south.
I first refinanced the mortgage of my primary residence to take out what little equity there was for some seed capital. I then primarily used 0% credit cards, occasionally supplemented with small personal loans from family.
My strategy was to buy bank owned foreclosures with cash - fixers that wouldn't qualify for most mortgages. I then rehab, and put a tenant in place with 1-yr lease. With the lease, I can use the anticipated rental income to help qualify for the cash-out refinance or ELOC secured by the newly rehabbed property. Use the cash for the mortgage or ELOC to juggle debt if needed and then repeat the process.
Investment property ELOCs have no seasoning requirement, so as soon as it's inhabitable and you can qualify for the loan, you can get some cash out. For cash-out mortgages, you usually have to have owned the property for 6-12 months. Sometimes you can't get 100% of what you invested out of a property, but you'll have the rental income each month.
I've only used residential loans so far. Investors can get up to 4 Fannie loans, then 6 Freddie loans. ELOC limits I'm not sure about, but may be limited to a total of the first 4 projects. After that, you're looking at commercial lending.
On a few I didn't take cash out and just used the rent to pay down the debt.
Using 0% credit cards is an entire topic unto itself. Between my fiance and I we now have at least 25 credit cards. I have a spreadsheet to keep track of balances, due dates, expiration of 0% offers, etc. Usually about half of them have some sort of 0% offer going on. Fee to utilize the 0% offer for 12-21 months varies from 2%-5%. Since 2009 I've usually had at least $50k+ in credit card debt at any point in time, usually all at 0%. At the peak, I had over $120k in 0% credit card debt. I went too far though, pushing my utilization to close to 90%, and had adverse actions taken by many card companies. Some closed accounts on me, others lowered my credit line. I've learned to show some restraint since then...
If you decide to persue 0% credit cards, don't just start applying for cards left and right. In 2009 I used the AOR (app-o-rama) strategy to acquire a handful at once. Card companies are hip to that now though, so better now I think to just apply for a new card every ~6 months. Those inquiries have a small impact on your FICO, and mortgage/ELOC lenders will ask about the inquiries. Not a big deal, but keep that in mind.
The most useful 3 cards for 0% offers I've found to be, in this order:
Chase (I have 3 Chase cards)
Citibank Diamond
Discover
All 3 seem to constantly mail me new 0% offers...
Capital One doesn't have offers as often but is also helpful.
I hope that helps.
Good luck!