The first thing you've got to state is your expectations from the deal. That is one of the most important thing before you start doing anything including trading. Just the same as business plan: you need to realise what you aspire to and what you want to achieve. This can be called exit position. Is should be clearly stated, vague limits usually lead to the loss of the trade as the trader has no idea when to close the deal.
The second thing is that you have to justify somehow your plan. You need to calculate the probability of success and your risks. It is an open secret that there are still chances of losing the money in every deal, so this should be stated clearly in order to move towards the third point.
Thirdly, after you estimated the risk, you shoud secure it. Many traders use stop losses in order not to lose much money in a single trade.That is a really effective tool to hedge your risks.
After it, you need to set your risk ratio, so that your overall trading will be benefitial in the long run.