Do your homework, carefully follow any details about this in the instructions, and look up some photos of the actual plane on the net. Usually they are parked with the gear down. If you have a specific question, feel free to come back here with it.
Go to an artist supply store, such as Hobby Lobby, and get some better quality artists’ brushes You won’t need the most expensive ones, and they are often on sale there. I buy the inexpensive variety pack with natural animal hair, avoiding the cheap synthetic bristle variety.
Put the propeller on last after all painting, decalling and detailing of the entire airplane, and if possible don’t glue it on. Check to make sure it will slide on and off the shaft easily during the assembly, and enlarging the hole slightly if need be before painting, etc. This can avoid it getting broke if something strikes it from the back by letting it slide off.
For other advice and tricks, I also suggest you subscribe to the FineScale Modeler mag. They throw neat stuff in each issue.