Starting with an AEG is a good move. The Cyma M14 is a decent gun. All you need at first would be an hop up rubber upgrade, you don't have to touch the gearbox, and its by far the most effective and cheap upgrade you can do on that rifle. Get a PDI W hop rubber, a Modify accurate rubber or a Reaps A+ rubber. There are other good rubbers on the market, but these 3 are easy to find and reliable rubbers.
The only thing that isn't very good on that rifle is the charging handle. It's made of really cheap pot metal, so don't abuse it and you shouldn't have any problem with it (you don't have to use the charging handle, its decorative only).
Keep quiet. Sound travels faster than BBs.
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