You are on the right track. You show amazing insight for someone who's just starting out.
Yes, your ideas are great and should produce great results.
Fliers in general are by far the best means of advertising there is - for most of us. They are the best return on investment, they generate good response, and they allow us to target specific neighborhoods (which is something most other forms of advertising can't do).
However, if you live in an area where houses are a block away from one another and have long driveways, you'll only be able to lay a dozen or two fliers an hour and they won't be all that effective.
Where I live, we can lay 70-100 fliers per hour / per person. That means we can do a good 600 or so a day. If there's 2 of us, we can do over a thousand. THAT produces results, always.
Anyway, on to your ideas. Obviously fliers themselves aren't anything new here. Most of us do it or have done it. There are numerous threads on the subject here. Just look it up.
But your first idea on a coupon is very good. And it's very important. Read "The Guerilla Marketing Handbook." There is an excellent chapter on circulars in there (fliers). Not to mention it has great insights for every other kind of marketing. In there, they state that consumers need a reason to act. They make several suggestions there. (Like mentioning FREE as often as possible, even if it's for a free estimate). But they say that a coupon is the most typical reason people will act on what they are reading - especially if it's one with a deadline (expiration date). Coupons are very important in all paper advertisements. If you don't believe me, just read your Sunday paper.
As for hand writing prices on each flier, this is a great idea as well. You'll find people will act sooner if they already have a price because that's one less step. They don't even need to call you to set up an estimate. They have most all of the information they need to make a decision. And it removes the guess work a lot of people go through ("Honey, why don't we call this lawn care service?" "Oh, I am sure they charge way too much. We probably couldn't afford it.") When they see your prices, they'll know right away if they can afford it or not.
I haven't yet gone the route of listing individual prices on our fliers for three reasons. 1) it would take considerable more time to lay fliers if we had to take time to evaluate each house and 2) because I am not usually the one who lays our fliers on doors. And I don't like to trust most of my employees to do it and 3) Our fliers already state our general prices on them. Most lawns in my area are about the same size so it's easy for me to do this.
So go for it. I think if you take the time to impliment one or both of these ideas you'll find you get very good results.
Just FYI, if you'd like to view our fliers, you can see one here;
Lewis Landscape Services - Oregon
"kickin' grass and takin' names"
www.lewislandscape.com - Portland Oregon Landscaping Company
landscape design Portland Oregon