tax season is getting closer.... newbie mistakes to watch out for? (in the middle of the reno on SFR#2)

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started an LLC, actively working on the renovation of SFR #2 (about $17k of anticipated reno costs). Daily trips to the home store for materials and doing all the work myself. Random piles of receipts, some probably still in random pockets :). paid a few people cash for labor. gonna need a large amount of labor shortly, typically hire friends and pay them cash.

I typically just go to H&R Block, another bad move?

I have a bad feeling that I am screwing myself. I go to the home store daily, sometimes more then once. do I really need every receipt? I have a dedicated credit card ONLY for reno stuff, would be great if i could just use the end of year statement as my list of costs but i have a feeling that isnt good enough. 

also, how bad is it to pay cash to a friend for labor, tax wise? typically a few thousand per year is what it adds up to @ $15/hr. is this money going to show as a profit even though it was actually 100% an expense??

and.... who does your taxes? im guessing not H&R block :)