I am new to Forex and have been doing FXCM practice account for 3-4 weeks. I have noticed that currency starts going up Monday late afternoon and by Thursday gets its highest point, and Fridays starts going down. I observed that over the past 3-4 weeks. Has it always been like this? Is there good and bad days to buy or sell?
boy if i only knew the answer id be rich 
the truth is price moves for a million reasons and it doesnt follow a particular schedule allthough there is a seasonality to some pairs like usd/cad for some reason closes january higher than it starts at the beginning of the month.
some other things…
Sunday evening is usually slow, followed by slow monday, tues, weds, thurs are all very high volume, friday is high but smart people stop trading around noontime. if you hold a positon overnight on weds you will pay triple the swap rate.
Any day can be a good or bad day to trade. You can make money any day and you can lose money any day. It depends on what kind of trader you are. I personally like highly volatile moving markets, doesn’t matter in what direction, as long as it is moving, and moving well. This is how I make money, this is how any trader makes money, the market has to move.
So I would say, the days where the market moves the most (which can be different all the time, especially with news involved), would be the days where you have the highest probability of pulling some profits.
Simply don’t trade a boring market, or a market that doesn’t move, when a market isn’t moving, you don’t either. You sit and wait.
Different for everybody.