A good Forex course is one that will not only give you the ability to trade, but also one that will give you good trading signals and a good system to analyze the market on and respond to with effective training. You don't want to do a trade on weak strategies and give yourself a poor education. However, understanding the market is not nearly enough to trading effectively. Having a good education is an excellent backbone but will not provide you with the actions you need to take. So when looking for a good Forex course, be sure to find one that is action oriented.
I recommend finding a Forex course that emphasizes the usage of expert advisors. Expert advisors are extremely useful when it comes to Forex trading. That is because you cannot possibly analyze all of the market data that is available and you have to rely on an expert advisor in order to gather up everything that is going on and put it into a simple trading signal for you to read. Instead of going it alone in trying to read several signals at the time, start with one that compounds the signals and specific market circumstances that you can trade.
As far as the course itself goes, I think it goes without saying that you need to find a traitor who is extremely reputable and experienced before listening to their course. There are many traders online or more than willing to give you a wealth of information and knowledge. Some of these might include Forex Institute. But there are many others out there. Just make sure that whatever course you decide to take, but there are many other people taking it as well and is an excellent reputation of delivering results to its students.
Finally, make sure that the course is geared for the strategy that you want to use. If the course is geared towards a strategy that you are not familiar with or one that you are not comfortable trading on, then take the time to reevaluate your strategies and find yourself a trading strategy that you want to use. After all, if you prefer daytrading it wouldn't be a wise decision to go into long-term trading. Stick to what you know!