Glad to hear you are developing a trading plan, they are invaluable, especially for shorter term trading.
Stop placement sounds simple, but is actually a pretty big subject @LeBigMac and I am a little pushed for time right now..........
Some traders place their stop as a measure of the maximum risk they are prepared to take on a particular trade, others can be more flexible (especially in a market where stop hunting is a sport, like CFD's or futures trading), and place a 'hard' stop a long way out of the action to protect their account, and use a 'mental' stop during trading. In this case (which requires a lot of discipline) you don't want to ever see your 'hard stop' hit, it is only there for emergency purposes.
Most often traders place their stop just below previous structure. That structure for a long entry would generally be a minor pivot where support was seen....so that previous support would need to be broken, at least temporarily, for the stop to be hit.
Another placement technique is to use a multiple or fraction of Average True Range.
