Tips on Squirting?

I've squirted twice now, both times have been while I'm on my knees being fingered from behind. I haven't done it since but every time I can feel myself getting there, it just goes away!! I think I might just be stopping myself because I can feel it happening and just focusing on it happening rather than enjoying myself. Does anyone have any tips or pointers on how I can loosen up or maybe anything to make it easier for me and my partner?