There's some very good advice given by the other posters.
A few thoughts I might add, from a piloting and server owner's perspective.
1> You start with three free scouts - N17-RUS and SPAD XIII on the Entente side, and the Albatros DVa on the Central side. Unlike what you may have read elsewhere, RoF is not
"pay-to-win". Both the SPAD and the Albie are among the top planes in the game, and in its proper time period, the N17 is also quite capable (although much trickier to learn to fly).
For these planes, you also get the various engine gauges and mods as well. All the time you can spend mastering these birds (particularly the SPAD and Albie) will return great dividends. The SP Fly Now missions are great for that, and even some time spent in "Career Mode" will help you. Also, you can still get some MP time in during that process -- New Wings Basic Training server is non-pvp (the only one, in fact), and it has various targets that you can practice bombing or dogfighting against, to continue improving your knowledge and skill.
If you're planning to join the pvp MP servers, you'll want to make sure you are familiar with the manually controlling mixture and radiator as well -- the expert servers will require you to manage those yourself, and if you learn those, you'll avoid the Number 1 problem in MP -- "How do I start my engine???". In those servers, it takes more than simply pressing "e".
Also, if you're going to jump into another player's 2-seater or bomber, good etiquette is to ask him first, and make sure you know the keys to work the turret properly -- it is possible to shoot your own plane down, and that is a *huge* No-No (see FF, below).
2> In icons-off servers, the next two key problems are: navigation and identification.
On the ground, the map will show the familiar triangle denoting your plane. Once airborne however, that disappears, and it's up to you to figure out where you are and where you need to go, using standard pilotage techniques (ie. visually seeing landmarks, forests, towns, rivers, etc.) and reconciling those with your map. That takes some practice, and again, Fly Now, Career, and our BT server can help you.
The second half is identification. It's easy to assume (or not care) that the plane you can see is an enemy. Many times it is not. SO, be sure you *know* whether that guy is a friendly, or an adversary. It's very important to your team and wingmates to get that right.
Further, there are only two (common) ways to be banned from a server. The #1 way is to shoot down a bunch of friendlies, and the second way is to use the chat function to harass, troll, and swear at folks.
By far, Friendly Fire (FF) is the main reason that server bans get set. Now, before you get *too* concerned about that, accidents do happen, even among our most experienced pilots, and everyone understands that, particularly in multi-plane furballs. If you DO make an FF mistake, own up to it, apologize, and try to improve. An isolated incident is usually not a big concern, but a pattern of repeated FF incidents is a problem.
Unfortunately, seeing airplanes without icons on is a skill. It will seem completely impossible at first, and it will take quite a bit of time to develop it. To help, set your Zoom keys to something easy to use (mine are on my joystick, for instance). You'll be making repeated use of them often. Also, while you're practicing in Fly Now, Career, and/or BT server, use the icons to find a target, and then try turning them off while still visually tracking him -- over time that will help you see them easier, and over time, you'll also start learning how to ID the plane by shape, and various visual features -- again, it takes plenty of time and practice.
3> Finally, don't be shy about just leaping into a MP environment. If you've been working on the previous points, you'll be well ahead of the newbie curve, and you'll find that most folks are quite friendly and willing to help. Expect to die -- a lot!
Typically, even experienced pilots get killed every few sorties (depending on what you're doing). A death rate of 1 death per 4 sorties is pretty good - 1/2 is not unusual. Pilots that fare better than that are typically in a group, often on teamspeak, and typically using more conservative attack strategies (nothing wrong with any of that btw -- it's just a different combat style).
In the real war, the life expectancy of the average pilot was typically just a few days, and many didn't live past their first or second sortie. In the expert servers, it's every bit as severe (except that you get to re-fly again right away).
Accepting death as a "learning experience" with a jaunty S! (salute) and a thick skin will go a long way towards having fun rather than frustration.
Speaking of chat, getting a headset / mic and using TeamSpeak is a very good way to: a> speed up the learning curve b> meet other pilots and squadrons c> enhance the MP experience.
That's a lot of info -- I hope you find it helpful. Welcome to RoF!