Demo account :
If you are new, you must try the demo account before starting Trading to build the skills and for a better experience. many trading apps provide demo accounts where you can learn about the behavior of the market in different situations.
Demo accounts are limited with trading versatility, most of the features you will have in all the available demo exchanges available are limited with features relative the real exchanges, it also lag and abandoned without updates from the developers. Instead of demo trading, go for paper trading instead, tradingview has the feature and you can virtually trade all the coins available coin market and coingecko and the view basically of all the features that you can see on exchanges, I think trading exchanges mostly mimic what tradingview has on their platform.
Reliable exchanges:
Choose that one exchange that good with the user and has a good background, Portability, Efficiency, security, and provides friendly interference in the market.
This is nothing but the truth, some exchange can be frustrating and they also intentionally liquidated trades, they gave glitches when there is high market demand which results into glitches and to cancel trades becomes problem, even with stop orders, they don't work those times and opportunity to make money becomes wasted, to avoid these errors it's better a research on best choice of exchange is done before trading begins.