I am really not yet the VSA expert you think I might be. I am still going through all the courses.
I am using VSA in combination with the "Better" indicators for MultiCharts. If both align, I take a trade.
On top of that, I also apply the candle confirmation techniques taught by inthemoneystocks.com
Personally, I don't trade FX. It's too fluid for me. With FX you might not get the usual VSA signs before a turn.
I would learn VSA in a slower market, like with the SPY. When that works out, you try it with a 2x,3x ETF, and then /ES.
As for time frames, I always compare three, like 3,6,9, minutes. Why not 5 or 10 minutes? Professionals tend to fool people by making big moves during the last 10 seconds of a 10 minute bar. I like to have those moves at the beginning of my candles rather than the end.
I am not sure what to say about the accuracy over longer time frames. I only trade intraday. I have tried longer term trading in the beginning, but I didn't sleep well when I had a trade on :)