One thing I want to touch briefly on is "rare drafting". Everyone wants to go home with good cards but you also want to win the tournament. Depending on how your store does it will depend on if you want to "rare draft" or not. Some stores re draft rares at the end of the tournament so find out if your store does this or not before deciding if "rare drafting" is right for you. Personally I will not pass a 20 dollar card like
steam vents 
just to get a slightly better card for the tournament although it does give you a slightly better shot at winning the tournament if you grab a
call of the conclave 
over that
steam vents for your selesnya deck first pick of the 3rd pack.
Check out the "limited information" collumn on the daily website. You can get some good information there.
I'll give you a brief summary of the format as I know it.
There are many deck archetypes that you can draft in RTR booster drafts. I will speak to some of the easiest ones to give you some ideas
The guilds
Azorius U/W
Golgari B/G
Selesnya G/W
Izzet U/R
Rakdos R/B
The easiest thing is to stick to two colors. There are other strategies some people can even play 5 color draft decks but they are generally more complicated and easier to mess up so as a newer player you'll want to stick to one of these color combinations.
Choose the cards which fit your strategy. For example if you're playing an aggressive G/W decklist a card like
trostani's judgment 
is underwhelming for 6 mana but if you've got a populate decklist with some slower creatures and/or some defensive creatures such as
axebane guardian 
then a card like
trostani's judgment will be an excellent addition.
First pack opened take the best card. Often times this will be a rare (or if you're rare drafting you'll just take the rare anyway). You really shouldn't pick what you'll be playing before you open the first pack (that is called force drafting and it might be a good strategy sometimes but it's probably best to play what you open). So if you open the first pack and find
armada wurm 
then that is a good reason to play selesnya but if instead you open
niv-mizzet, dracogenius 
then maybe you should go izzet.
Drafting is a very skill intensive format where you not only have to draft well but you also have to construct your deck well and then be a good player in order to win the tournament. Given that expect to make some errors for your first time but learn from them.
Deckbuilding:
You want either 17 or 18 lands no more and no less. There are cases where more or less would be correct but having a good mana base is not something you want to screw up. It's nice if you can grab a couple of cards like
golgari guildgate 
to help you get both colors online but a 2 color deck should be fine even without the guildgates. If you have cards like
ogre jailbreaker 
then the gates become slightly more valuable of course. Gates and keyrunes and
transguild promenade 
become more important if you find yourself drafting 3 colors.
Creatures and spells can be a little more tricky and it really depends on what kind of deck you're building but you want there to be some balance. Keep the deck to 40 cards. I can't really tell you ahead of time what is correct (it depends on the type of deck you draft) but I find myself playing 18 lands 14 creatures and 8 other spells pretty frequently. I wouldn't play less than 12 creatures unless I was playing a specialized theme which didn't rely on creatures (doesn't happen very often in limited).
The acronym BREAD is used a lot.
- Look for Bombs
- Look for Removal
- Look for Efficient spells/Evasion.
- Look for Aggro (1-3 mana creatures to get in the early damage)
- Take the Dregs.
Early on this is what you'll look for but the later it gets into the draft you may have to adjust things. At first chaos imps 
is amazing but in the last pack if you've got niv-mizzet, dracogenius , and 2x chaos imps already then another one will not be of much use to you becuase you've already got 3 creatures of 6+CMC which is about all most decks can handle.
