This is a great question. I had the same experience of doing well early and then having more problems later. I am a very curious person and I am a trier. Once I know something can be done I will never give up. This sounds great for trading right? It is, but also it means that I just keep trying things when I should give up and focus on one thing! So I tried opening range brakes, I tried reversals, I tried momentum trading, I tried trend trading, I tried scalping, I tried it all! I tried going live after 6 months in the simulator and it was a total disaster. I reacted emotionally after a big loss and tried to make all my money back on the next trade and lost twice as much. So I went back into the simulator and then I tried going live again a few months later and it was better but still not good. Then I mostly traded in the sim and sometimes when things were going well I did some live trades but I knew that I wasn't there yet. I finally got to the point where I had come full circle. I had tried all the different things I was going to try and I was starting to look back at what had worked best for me and came up with what I really wanted to stick to.
For me it was a matter of keeping things very simple and doing very few trades. I decided to do one five-minute ORB. No trading in the first 5 minutes! Had to wait for that first 5-minute candle that close and then look for an entry. Then I would do one VWAP break, usually after 9:45 or so, and only enter on volume. I would not do any trading after 10 am. Working this plan really helped me in a few ways. First, if I had a down day it would be a small down day. Things can only go so badly when you just do two trades. Also, this kept the fees down. So once I could do that consistently and I was getting decent results and, most importantly, it just felt like a normal thing everyday, I went live again and have been live since then.
That point of going live was after a year and a half of trading the open before my job of running my small business every day so it took a while! I track my 10 and 20 day averages, focusing on R multiples not money, increasing my risk when my 20 day average is above .5R and now sometimes do another one or two trades and sometimes trade a bit after 10am.
So anyway, finally deciding on two simple trades to focus on was what did it for me. And doing just one ORB and then waiting for a volume entry on the 2 min. chart for a VWAP break kept me from making entries based on reactions instead of rules.