What do you need to put on trade after trade and be successful over time?
Entry rules, exit rules, money management rules, and stop placement rules.
This thread is not that. There are other threads here at ET, in books, across the web, et cetera, that will give you hard and fast trading system rules.
Trendlines and the resulting channel lines are just a useful way of looking at a market, one that many people use to get into and out of trades.
But, they still have those rules. If this happens, I do this. If that happens, I do this.
So, essentially, trendlines are tools, and rules can be built around them. But there are no hard rules in this thread. It is up to you to either find some rules you can follow easily or make some rules that you can follow easily.
And about that other thing: the real answer is - we could all be paper traders. You must decide if you are getting useful information out of this thread.
If you don't understand trendlines, you don't have to use them to be a successful trader. Check out any number of other ways of looking at market data, market profile, volume studies, or any number of indicators out there. There's a bajillion of them.
And one last thing: don't take my word for it. I'm actually just a daschound at my master's computer. Pick up any number of well regarded books - Technical Analysis of the Financial Markets or Futures and Options or whatever. Read what other people say about trendlines, or whatever other tools you decide to use that can alleviate your doubt.