I think purely systematic trading is very hard, because it is inevitable you will experience a drawdown in the future greater than the maximum shown in historical testing. In the real world, what do you do when this happens? It would be very hard to stick with the system when this happens, because you will be asking yourself is this just a drawdown or has the market changed?
The basis of my trading is a selection of mechanical systems, but I put a discretionary filter over the top of it. The reason being that systems are good for modelling patterns and the like, but can't take into consideration other things such as news, economic announcements, political situation, sentiment etc.
I am constantly tweaking my systems, incorporating new ones and dropping off ones that haven't been working too well. Combined with my discretionary analysis as the final filter on when to do a trade, I am attempting to stay ahead of the curve and adapt to the current market.
I would probably make money just sticking to the system religiously (albeit with larger drawdowns), but I would be nowhere near as confident of long term longevity than with my current approach of constant adaption + market reading experience.
For example, the current war situation has had an impact on my systems. Instead of just sticking my head in the sand and trading through it, I have saved a fair bit of angst and dollars by cutting back trading size, and focussing on shorter time frames than I usually do.
With regards to trading ideas, no one is going to give you their tried and true models. I made a post a few weeks ago outlining typical CTA systems. These probably aren't viable for an individual trader unless you have a fairly large account.
If you are developing systems for a single market, I would definitely look at intermarket patterns.
Hope this helps.