I have a different approach for pricing than by the hour.
I try to mostly price by the JOB, The reason is when you become more efficient by 1) being more skilled or 2) more efficient equipment, the profit per hour goes up.
Lets say you charge $30 an hour to trim shrubs. Well what if when starting out, you did 4 shrubs in an hour. And then later on you became better at hedge trimming, and you also upgraded from that Black & Decker electric trimmer to a bigger, more powerful gas hedge trimmer. Now you can do 8 shrubs in an hour. You just trimmed 4 shrubs for free with the hourly method!
This is not to say that taking into consideration the amount of time is bad. There are certain things I group into a second category that I assign more of a "weight" to because 1) it will simply take longer to do than usual or 2) it will require more physical effort to do. For example, if someone wants me to use a chainsaw to cut up some downed trees, you better believe I am gonna charge more per minute/hour/whatever than if I was just sitting on a mower for the same amount of time.
Examples of things that will take more time but arent necessarily "harder" are weedeating big ditches that can't really be measured out by linear feet, areas that aren't accessible with a larger mower, etc.
Now, in perfect conditions, I have, in my mind, a minimum charge for going to a property. What is the minimum that makes it worth my time to drive out there and unload? I then have a minimum charge for edging and a minimum charge for trimming. So, if they just want a mow, the minimum charge is X, mow and trim, minimum charge is Y, mow trim and edge, minimum charge is Z, etc. And as I said, thats a MINIMUM. Based on experience, for that minimum price, I will mow such and such size area and put such and such amount of work into trimming/edging. If it will take me more than a certain amount of time to edge or to trim, then thats even more added to the price to trim or edge.
For trimming around objects like large rocks, trees, etc, I count them and charge X amount per object. For linear trimming, I know that every step I take 2.5 feet. So I walk the area and figure out the linear feet and multiply it by how much I've found, by experience, is what I want to make per foot (based on how long it usually takes). For areas that are thicker and will take longer, I charge a little more.
The same applies with using my gas push edger. For driveways that just need to be maintained, that are already edged, I charge x amount per foot, and I also have a minimum charge for edging. For driveways that are pretty overgrown and need to be "prepped" to be maintained, I charge at least double per linear foot
So I base my bids on minimum fees for the stop, for each indvidual each task, along with a "hardness" factor for areas that will require special attention or just be more work. Hope this helps.