I took security deposits equivalent to one months rent. 

I look for the best applicant.Someone that has had same job for a couple years, someone with more income that can pay the rent.If I have to give a little one one of my criteria then I get a larger deposit, usually 1.5x the rent or first, last and security.Sometimes you have to keep looking to get a good applicant.I have been luck I usually get 30 people inquire and 4 or 5 apply.Section 8 can offset a low creidt score since their rent or part of it is guaranteed by the government.

Am I justified in using his security deposit to repair the damages?

In our area, preapproved letter from a major lender or a credible local broker, funds for down payment, deposit check, release of most and if not all contingingiences.

Ask if they currently have the cash for security deposit and first month's rent.Ask why they're moving and when they plan to move.Ask if they are indoor smokers, outdoor smokers, or nonsmokers.Ask if they have pets.Ask if they have ever been evicted or late on rent.Ask if they've ever taken a landlord to court.Ask if they've ever had trouble with bedbugs.Lots of these questions can be on an application really.The following isn't exactly what to ask them, but good tips seeing this is your first rental:Typically, the longer their story to you, you'll find the more they're hiding.If a couple breaks up or roommates fight, don't let them make it your problem.

As a part of the raise you need to ensure that you budget for cap reserve, closing costs, funding the operating account, first years insurance, utility deposits, and other contingencies.  

Deposit Power is the name of the company.

Even with my two month vacancy last year, I had two "near misses" from tenants that ended up not showing up to sign the contract and pay the deposit after verbally agreeing to rent after an initial showing.  

One time an angry tenant (he thought he was getting his entire deposit back that day) ran after my car spitting and swearing while my youngest child was with me.  

Make sure you get all the deposits too. 4.)