Before I had a tumbler I would just use 0000 steel wool to clean the outside of the case and get sore fingers. Wet tumbling is what I prefer now because I have so many firearms that throw perfectly good brass away. Wet tumbling is the best method for removing any embedded dirt or grit from the case that will scratch your dies. If you do not have a tumbler then steel wool will remove any grit from the case and any of the cleaning solutions below will remove the carbon and dirt.
I used the highlighted cleaner below for cleaning before dry tumbling with walnut media. And be forewarned the longer the brass remains in this cleaner the Pinker it will become. Meaning it isn't a overnight soaking solution.
Homemade Firearm Cleaners & Lubricants
http://www.frfrogspad.com/homemade.htm
Chemical Case Cleaning Solutions
While tumbling cases in an abrasive media provides the best finish, extremely dirty cases can be decapped first (using a non-sizing die) and then washed in one of the following solutions. The final rinse in soapy water helps prevent tarnishing. All of these methods were approved by Frankford Arsenal and will not weaken your brass.
A 5 percent solution of citric acid (available from your drugstore) and warm water for about 10 minutes. If your water is very hard increase the amount of citric acid. You can add some Dawn™ or Cascade™ dishwasher liquid soap (which does not contain ammonia--be careful some do), 409, or Awsome to the solution for extra grease cutting ability. Follow with a rinse in hot soapy water (Ivory™ works well) and allow to dry. Don't overuse the citric acid or the brass may discolor.
A solution of 1 quart of white vinegar and 2 tablespoons of salt. Soak with some agitation for 15 to 20 minutes and follow with a rinse of soapy hot water and allow to dry.
A solution of 1 quart of water, 1 cup white vinegar, 1/2 cup lemon juice, 1/4 cup laundry or dishwashing detergent, 1/8 cup salt. Soak with some agitation for 15 to 20 minutes and follow with a rinse of soapy hot water and allow to dry. This may leave brass with a slight pinkish cast which will disappear with a short tumble in media.
Military arsenals use a heated 4 percent sulfuric acid dip with a little potassium dichromate added. The solution is heated until bubbles rise slowly without it boiling and the cases are dipped into it for 4 -5 minutes using a basket of copper screening or plastic. A final rinse using plain hot water is followed by hot water with Ivory™ soap in it and the cases are left to drain and dry. Because of the use of heated sulfuric acid this method is probably impractical for home use but is given here to show what can be safely used.
I was reading about wet tumbling and LemiShine being hard to find that contains citric acid that you add with dishwashing soap for wet tumbling. One of the poster said he used Kool-Aid as a replacement for LemiShine, I looked up the MSDS sheet for Kool-Aid and lemon-lime Kool-Aid is 97% citric acid.
So you can try the cleaning solutions above or just some dishwashing soap and Kool-Aid agitated by hand.
Below the instructions for my STM wet tumbler using stainless steel media.