Fertilizing

HI all,

I am offering Fertilizing this year and i haven't really done much of it. How do I know how much to use on each property? I know you need to know the square footage. How do you guys measure the yard. Also what would you recommend to use to spread the fertilizer with? I use one of the walk behind spreaders that i got from the guy i bough my business from but its hard to tell how much is coming out. The numbers don't seem to work for me, but i also think the machine is not set proper.

If I buy a brand such as Scotts, it tells you what number to put on the machine. The stuff I buy is from a farming store and the bag dosent tell what setting to use. How do I figure that out. I hope this makes sense. Thanks