Just my .02 as someone who is new to being clipped in. I'd start with "comfortable" places as far as being clipped in goes...your subdivision, an empty parking lot, park, etc. I spent several days just going in circles in my cul-de-sac, then I moved out into the subdivision, then to the park and then on a group ride. Once you're comfortable with those things hills won't seem quite so scary. I figure if nothing else, if I find a hill I can't pedal up I can always walk it