I've been asked by a homeowner to give an estimate for the following work. Her backyard slopes down slightly from the house for about 20', then the slope increases significantly (I'd say about a 20 degree angle) for about 60' before leveling back out near a paved path at the back. There are about half a dozen mature trees scattered in this steep sloped section. She wants the sloped area leveled off in tiers, which means building some type of retaining walls, bringing in dirt and then I would think some plantings to prevent erosion (wooded area in general - doesn't look like grass would grow too well but maybe a shade mix would). When I first looked at it I told her it was a bigger job than what I normally do and that I don't build retaining walls and being a part-timer it would take awhile if I were to do it. She said she had gotten other estimates and would really like me to consider it and give her an estimate. She has patiently been waiting for a few weeks now. I would need to go back and get more specific measurements of the area but.....how do you pros estimate a job like this? Also, any suggestions for leveling the slope off in tiers without using srw? Part of me would like to do this job to try to expand my horizons but another part says "a man's got to know his limitations" and leave it to the hardscaping pros. I don't want to do a half-*ss job if I were to do it. With all that said, if you could tell me the proper steps/methods for estimating a job like this and offer any insight for creating the tiers (without srw) I'm sure it will go along way in helping me figure out if I should give an estimate for this job or politely decline. ( I know with the limited description of the site it's a little tough to envision). Thanks for any constructive advice you can offer.