Place them at major intersections for maximum visibility, BUT spread them out adequately so that you do not attract code enforcement officials that can tell you to remove the signs or face stiff fines.5.  

Also when I go to these auctions I face stiff competition their are professionals that go to these auctions everyday of the week so try to attend one beforehand so you can see how everything works.

Now that mailers don't work so well, they just try to stiff the next guy they pass the deal on to. 

You can't just "make up reasons" to file a mechanics lien, you had to have been contracted by the owner (or the owner's contractor) to perform improvements to the property, and the penalties here for a fraudulent lien can be stiff.

Drywall mud will be much easier for you to work with than Diamond (which is probably best applied by a professional).I'd try to knock down the high spots with a stiff-bladed putty knife and scrape off any crumbly or loose areas. 

Also I see a lot of bandit signs and "lawn darts" (little flags on a stiff wire with a message on the flag).

You need a stiff spine to make these work IMO.

This is the product of a bunch of years run up in the market, too many people watching HGTV shows and think it is so easy, and the gurus selling their BS programs suggesting to newbies to start wholesaling as their first go at investing since it can be done with no money, no credit, no brains, and no skills.You are now seeing and receiving the product of these circumstances first hand, good luck stopping it yourself, only a nice stiff market correction sending many to the poor house will stop it for a bit, then the cycle will repeat again.

What we do to hedge against a possible short-term depreciation cycle is that we look for value add RE that ideally we purchase below retail (but competition is stiff so purchasing significantly below retail requires networking, marketing, etc). 

Every real estate strategy, every real estate investor, faces stiff competition for the deal.