You can start screening your lenders now and meet with them to determine which lender you'll want to work with and when you have your property lined up you can request the pre-approval letter to limit the inquiries on your credit.  

They tend to be very grateful for the home, but you do have to screen carefully.

Even though I will budget for vacancies, my biggest fear is that I'll initially make a few bad choices in the screening process and I'll have to evict families.

If you have nice furniture, huge big screen TV, high end cookware, etc... but your bed is uncomfortable or your sheets feel cheap, your guests will come away with a bad view of your place. 

My advice is to make sure you do a thorough tenant screening because they may be there for a while. 

Use www.postlets.com to advertise and then vet tenants by going to BP resources and use the tenant screening provided.Most important to contact prior landlords personally as they really can give you the best info on prospective tenants.This whole process doesn't take much time and I would rather take the responsibility of tenant screening than to abdicate what should be your responsibility.It's not like rental agency is going to give back fee if you get a horrible tenant who stops paying and needs to be evicted so might as well do it yourself.

Your phone will ring off the hook with people trying to sell you spots on radio, tv, paper, and online. 

This technique often leads to a management nightmare as they, or the management company they have chosen, are not prepared to properly screen tenants and manage a rental property in a distressed community.

I wish my tenants would all pay a years rent when they get 5-6,000 in a tax refund, instead of blowing it on a buy here pay here car down payment.or a 60" TV

That is where good screening and impeccable references come in.