[[TA]LoSt]

I don't know if my way is the best, but I just have my sentries hotkeyyed on 1 with my main army (One of the useful yet bad habits of playing Protoss - having all units on 1 hotkey) and just 1a then f click f click f click really fast. There's no need to have your sentries on another hotkey as it would just delay both their movement by having to 1a2a and their forcefields by having to swap hotkey groups.

At silver level you shouldn't be trying to make things harder for yourself, you'll naturally get faster and be able to do multiple group hotkeys with different spellcasters however for now I think it's just best to have your zealot/stalker/sentries all on one hotkey and f click as fast as you possibly can.