When managing an open trade, is it generally more effective to set a rigid ‘set and forget’ profit target and stop-loss from the start, or to use dynamic adjustments (like trailing stops or scaling out) as the trade evolves? 
What are the biggest pros and cons of your preferred method?
A golden rule for me is to never move the SL further away from entry.
But in managing a winning trade you should also consider adding to the position, especially if your entry got you into a trend-following trade, and the trend remains consistent.
When I was new to trading, I’d often average down on losing positions, a big mistake that usually led to greater losses.
Now, I never add to losers. My stop-loss is set where my trade idea is invalidated, and if hit, I’m out.
For winners, I trail my stop with the 100 VWMA, which I find adapts well and provides breathing room, especially during news events.
It is if your testing shows that that’s more profitable than other ways?
I don’t believe automated trailing stops are ever a good idea for forex trading. I know millions of people disagree. But I don’t know any successful or professional traders who do.
I don’t like scaling out. It means my position size is biggest early on when the risk is higher and when the trade moves into profit it gets smaller. I’m still thinking about this one. I know that some good traders may disagree on this one. It’s a puzzler(?).
I don’t.
My trading plan involves only trades which are entered with a single click, with all the trade management built in automatically: stop losses and their subsequent adjustments (if any), targets and all.
No further “management” required.
It takes a lot of the pressure off, and removes much of the emotion.
It’s not necessarily quite the same thing as “set and forget” like some people do, if they’re entering by buy-stop or sell-stop (though it can actually be that, as well), but it’s a nice “enter and forget,” and I’m just used to it and wouldn’t want to trade any other way.
If the price moves the right way, and it turns out well, I eventually (but not quickly!) move the stop loss to break even. And sometimes even move it a bit further, if it still goes really well.
But (like @tommor said up there) I never move a stop loss in the other direction, whatever happens.
And I don’t set it to trail with an automated thing, either.
I like keeping things simple; fixed targets and stop-losses are my go-to. Way less stress, way more clarity.
Yeah, trailing stops are good, but I’ve got that old-school rhythm in my trading. Fixed levels just click for me. No second-guessing, no drama.
I might miss out on some of those big runaway moves now and then, but honestly? I’m fine with that. I’d rather lock in steady wins than overload my brain trying to chase every last pip. Less on the plate, fewer regrets later. Works for me!
This is my approach, too.
Those “runners” are maybe great trades for other people, who I imagine have far rougher and wilder equity curves than I do. I no longer envy them. 
I don’t envy them, either. To be honest, I don’t very often even believe them.
(I don’t mean necessarily about individual trades - more about their overall profitability, if they claim to trade successfully, long term, with a high R, as some do.)