As the boyfriend/husband of a lady who likes to squirt, all I can say is practice makes perfect. Guiding someone with real-time suggestions is certainly an option - but sometimes that can be a bit distracting.
Discuss what works best for you before hand - and suggest that he learn to read your arousal clues. I can read my wife like a book, I know what's working and what's not by her physical reactions. Level of lubrication, breathing, sounds, elongation of her vagina. and when I'm not getting it - she will gently suggest that I 'move on' or try something specific.
It's like a symphony - with you as the conductor and instrument.
If your guy is at all interested in your pleasure - he will welcome the suggestions - if not - find someone who is more interested in you than himself!