We were originally on Peachtree accounting.  We made our change-over in-house.  First we got the manufacturing modules up and running.  I felt the manufacturing part was the most difficult and time consuming.  If you already have the manufacturing part done ie: part numbers, cost accumulation, etc., that's most of the battle.  
 
Our next step was to get the subsidiary ledgers operating-Accounts payable, accounts receivable...just one at a time.  If you are small, that shouldn't be too bad.  Entering vendors, beginning balances, running 1-2 months on both systems, then cutting over.
 
If you haven't already done it, you need to setup the GL account numbers.  Use the same ones you already use, if possible.
 
Once the sub-ledgers are humming along, do the G/L.  You have to post the info for it to show up in G/L.  Go to GL-O to post.
 
To do some learning and trying, you can copy the current company - call it Test or something.  Then tryout whatever module you pick to start on.  Let's say it's AR since you already have sales up and running.  The invoices would need created and POSTED in the SO module.  Do one invoice and post to the GL via GL-O, do the proper accounts get debited and credited?  If not, then start adjusting the account numbers for the Item Class in SM-C.
 
I know that most people tend to wear many hats in a small company.  However, you would get a world of know-how and knowledge on the system if you do it yourself.  That way when problems arise, there is a deeper understanding how the system works.
 
Give me a call if you want to discuss this further.