The $1 per minute is definitely just a starting point and you must figure out what your expenses are in order to properly price your work. BUT, if you are just starting out it is very hard to determine what that number is until you have been in business for a while. There are so many variables that it is impossible to just sit down before you have ever mowed a lawn, crunch some numbers, and know with any level of accuracy what your operating costs are going to be. Usually when guys start out they take on all kinds of work which makes it even harder to know what your operating costs are. As you do this for a while you start to realize that some jobs are impossible to make anything on. After a while you start to recognize those jobs/clients BEFORE agreeing to do the work so you can avoid wasting your time on stuff that isn't profitable.
Anyone asking for help with estimating isn't the type of guy with lots of employees and hefty notes on all new, top of the line equipment. If you are just starting out, working by yourself or just with a helper, you will do okay if you can average a dollar a minute at each job. After a full season you can more accurately figure out what your true operating costs are and adjust that rate accordingly. As someone else said, precisely time all of your work. It will make it very easy to see which accounts are the most lucrative and which ones aren't so great. As you get more work you will be able to continue tightening your routes which can drastically increase profits. At least for me, my minimum charge is $25 for a mow and blow. About half of my accounts don't take me 25 minutes to complete so that helps offset the accounts where I'm not quite hitting that $1 per minute. There are several add-on services that you can upsell that you can make way more than a dollar a minute. These services are much easier to sell to your regular mowing customers so even if you aren't making a huge profit on your dollar a minute customers there is still potentially a lot of value in maintaining that lawn. The customers to avoid are the ones that call up looking for every other week service. They'll tell you, "it just doesn't grow in the summer so it doesn't need to be mowed every week." They are looking to spend the minimum on their property so they are unlikely to buy other services from you, and even if you are doing a good job, their lawn is always going to look like crap. I used to take accounts like that and I can't remember any of them that turned out to be a good for my business. They screw up your weekly schedule and they never result in new customers. The guy across the street sees your truck out there, notices the lawn looks like crap, and assumes you suck. Not a great recipe for picking up new accounts on that street. Come up with a standard system for quoting prices for a standard package of services. Get good at providing those services before you start adding new ones. If and when you do start adding new services, count on losing some money on them at first while you figure out how to estimate your time and determine what people in your area are willing to pay for such a service.
Keep your expenses as low as possible for your first few years, develop a niche and stick to it, don't be afraid to say, "I'm sorry we currently don't provide that service," and make damn certain you are setting aside money for taxes. That check to uncle Sam right as the next new season is just getting started will kill you if you haven't been planning for it all along.
Lastly, with regard to pricing work by the hour - that might work for 1 guy in a hundred. For the other 99, that is NOT a good idea. Customers are going to feel like they need to be watching you to make sure you are working the whole time you are at their property. If you need to stop to gas up a mower is that now on their dime or would you pause the clock for the customer - at least if you see them looking out the window? When you are giving the quote, potential customers are going to think your prices are crazy high. (customer: "SIXTY DOLLARS AN HOUR TO CUT MY YARD???!!! ARE YOU FLIPPIN' CRAZY???" insert expletives...repeat) Also that must complicate your daily work completion tracking and billing system immensely. I honestly can't think of one single advantage to pricing lawn care like that. That seems a lot more like the customer is the boss and you are just an employee. I personally wouldn't like that arrangement from either side of the deal. Maybe I missed something in that post...who knows.