Here are just a few things that might be useful for a new player that has started a Ranger or even a older player that is not familiar with the class.
A Ranger is a rogue and in some ways you can almost play it like a assassin. What I mean by that is, you can attack from stealth. Now you're not going to get the 1 shot kills a true assassin gets but you do get a nice stun effect which allows you to follow up with some real damage.
So in order of what to do:
1. Go into "hide" mode
2. Target the NPC or even PvP player you are after.
3. Check to see if any side is unshielded on your target.
4. Use the appropriate attack arrow key to hit the unshielded side , if any.
What happens is you instantly come out of stealth and fire your bow, result is, the target is stunned for approx 5 sec!
5. Drop your trap
6. Fire off your pin down combo
7. Fire off your best high damage combo
8. Fire you salvo combo
The NpC should drop dead right at your feet!
If you are still below level 24 or so you can switch to melee and fnish him off if he didn't die as expected! After level 24, your melee combos become pretty useless when compared to the massive damage of your bow. After level 19, you don't get ant new melee combos

Now what should be on your hotbar?
I use the newest and 1 level down on salvo, you can fire off one and while its on cool down you can fire off the lower level combo. Heartseeker, LOVE IT, USE IT!!! This is without a doubt the best combo you have! Next in line is your best Bleed effect, current level combo and 1 below that. Last in line is your amor ripper.
I play 8 toons and my Ranger I enjoy the most

Kobe