To join squares:
With Right Sides facing, hook through corner stitches, draw up a loop, tie the loose end to the side of the loop it's attached to with a reef knot. Tighten loop and DC across, weaving in the end as you go.
To edge the finished blanket:
Join wool as above. HTC along until you get to a join or corner. HTC in last st of square, ch 3, sl st in 1st st of next square (or same st if at a corner). Wiggle around and sl st in previous HTC. In the loop you just made: HTC, HExTC, 2 ExTC, 2 HTC, picot, 2 HTC, 2 ExTC, HExTC, HTC. HTC along until the next place you want to put a heart!
Abbreviations:
DC = Double Crochet
HTC = Half Treble Crochet
Sl st = slip stitch
Ch = chain
HExTC = Half Extended Treble Crochet - yarn over twice, through st, yo, pull through st, yo, through 2 loops, yo, through remaining loops.
ExTC = Extended Treble Corchet - yo twice, through st, yo, pull through st, yo, through 2 loops, yo, through 2 loops, yo, through final 2 loops
If anybody would like to tell me what those last two are really called, I'd love to know!!! 