I would recommend for a beginner spending what you can afford within a budget of $300 to $600. Any cheaper than $300 and the guitar will not be of good quality to last and may not even stay in tune. Over $600 is too much of an investment if you decide not to continue playing or you find you don't like the particular guitar you have bought.
Hardware wise, get a guitar with two pickups at least. One at the bridge an done at the neck. A guitar with one pickup is not enough, you will be limited in sound, three pickups is nice to have but you may not need or actually use the middle pickup.
If you can get a guitar with a humbucker pickup this will help you get a beefed up sound for rock. With a single coil pickup you can always use amp and pedal settings to get a good sound also so don't worry if it is a single coil.
You don't really need a tremelo unit or whammy bar at this stage. You will need to be playing quite a while before you can use it. If you do get a guitar with a bar, get it fixed in place while you begin to play.
Check on line for the best price but also go to your local guitar store to try out guitars and to haggle for a best price too.
As for the brand, if you have heard of the brand it is of good quality. Like Fender, Gibson, Squier, Epiphone, Jackson or Ibanez. Research the guitar on the net before you actually buy it.