1 when cutting in stairs always remember that most architect consider stair's to be wasted space so the stairs though not always are usually drawn in tight ,

2)an  easy way to figure if you have enough headroom is to go to an existing door oppening for a typical door and measure it from the floor up it should measure 82inch 3/4 then level up from the nose of a stair tread and measure if it is more than 82inch 3/4 you should be fine,

3) 38 to 42 degree stairs are typical though you want to go closer to the 38 as to keep the stair's not as steep as you get older you will appreciate it,and it is better for children who have a tendency to run up and down stairs

4)you do not want to go more than 8 inch for a riser

5) I like to put blocks between the stringer's at the center or halfway down the stringer it keeps the preasure even where you need it most and helps prevent squeek's

6) people tend to say I want my risers to be this tall and steps to be this long which is a common diy mistake what you should do is measure from the top of floor to the bottom of floor where stringer will rest and then devide it by 14 or 15 or whatever it takes till you get close to 8 inch without going over then make a pattern and cut only the top and bottom of the pattern, then set it in the stair hole and check your clearance for head room, if I have alot of head room I might change it to 1 more amounts of steps which will make the head room less but makes the stairs less steep and helps when moving furniture downstairs and again as you get older .but remember not to go below 82 and 3/4 inch for head room,

7) this is a very important step always cut the bottom of the stringer the amount of your tread, example if you are using 2x12 treads cut 1&1/2 inch of the bottom then if you riser is 8 inch measure down 9&1/2 inch and put the top of your stringer on this mark when you put your tread on it will be 8 inches to it and on the bottom since you cut of 1&1/2 inch of the bottom it will measure 6&1/2 inch but when you put your tread on it will measure 8 inch also.

8) another common mistake is when you measure from top to bottom you will have a tendency to add an extra step, if you devide by 14 you should have 13 treads but go ahead and cut 14 it is easier to have too many and cut again then not have enough and have get another board .treads can be as short as 9&1/4 long remember that you can still use a 2x12 tread so your foot room will be the same. and if you need more head room you can adjust your tread as well as riser's   

I hope this helps you out , and good luck the best set of stairs is the one that is easiest to go up and down and still have the head clearance you need

Stringer: the board used to nail your riser and tread to;Main Body or frame

Tread : the horizontlal part of the stringer

Riser: the vertical part of the stringer

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