For tapered legs, use a tapered leg jig on your table saw (you can purchase a jig, or rig one up yourself like we did here: http://dateswithdrywall.com/our-diy-mid-century-inspired-bed/). For our bed, we tapered each side by half an inch at each end, starting 7.5 inches from the top of the leg to accommodate the bed frame sides (which are made of 2"x8"s).

After all four legs were tapered, we pre-finished the legs and frame sides (all the 2"x8"s) by carefully sanding/sanding/sealing with polurethane and letting the finishes dry per manufacturer's instructions. Then, we pre-drilled pocket holes in both ends of unfinished 2"x4"s and finished 2"x8"s, before attaching them together using construction adhesive and 2.5" wood screws spaced about 2" apart. The 2"x4"s will form the supports for bed slats, and are attached .5" from the bottom of each 2"x8". We did this for each side (left and right), making sure to arrange them so that the best-finished sides of our 2"x8"s were exposed on the outsides.

We attached tapered legs to each end of the two (left and right) frame sides. We found it easiest to do this step upside down, so we could properly align the top of each leg with the top of the frame side while screwing 2.5" pocket screws into our pre-drilled holes.

Next we attached the top and bottom 2"x8"s, again after pre-drilling pocket holes for each. We did this step upside down, also, because it became even tougher to keep our edges properly aligned.

Finally, we added fifteen unfinished 1"x3" slats as mattress support (you could use as few as thirteen of them, but we added a few for extra comfort). Each slat was evenly spaced and secured to the left, right, and center slat supports with wood screws.