At the end of each flying session if you pull the fuel line, connect the booster and start the engine to run off any residual fuel left in the crankcase it will lessen the chances of leaving raw fuel inside. Remember that alcohol absorbs moisture and nitro forms nitric acid.
I do not have a Baby Spitfire but I have its brother the Spitzy .045 (the one with the tank on the bottom). Runs nice.
George