No matter how you've been contacted your focus should remain the same, if lawn care is something you are considering when the grass is finally visible, do your homework!
With Google at your finger tips it isn't hard these days to find information on anything, if you do a little digging. Sites like Homestars who collect customer comments on many service industry businesses make it even easier. But be aware if you use this site when checking out a company, especially when you have too many polarized comments,. I would trust a company with consistent 7 and 8's over one that yoyos from 0 to 10 constantly.
For some, price may be an issue, but you need to ask yourself if that, "too good to be true" price is going to lead to a barrage of calls to upsell you extra applications like aeration, grub control and other services to crack the piggy bank. Many times companies use scare tactics like, "you could lose your lawn if you don't get this application," and it works. If you are unsure, ask for a service call and a technician who can show you the issue before you sign on the dotted.
Read between the lines. A lush beautiful lawn for $6 dollars a week may sound nice until you realize that is averaged over 52 weeks and not a 7 month lawn season.
Also an initial price may only include a couple of Fiesta weed controls and if you need more than two sprays the charges will start.
Read the fine print! Is the company you are signing with a continuous service company. In other words, are they going to keep coming year after year until you tell them "no". In some cases that won't be enough and you'll have to jump through hoops to get a cancellation number. Sadly this is how some of the dinosaurs still operate.
Understand, a bigger company will likely have a greater share of unlicensed and novice technicians who will be learning their trade on your lawn. Mistakes are made by the best, but I've also seen some real bone-head applications by technicians who didn't know any better.
Most importantly, use your gut. If you have a good feeling about who you are going to use, take the plunge. After all, the reason you are considering this is to take the stress off of having to do timely applications yourself. If the company you hire is adding to your stress level, close the door and go a different direction.