Hi, dude/tte! Always good to see someone who does his research before starting to play instead of just diving into cash games like I did when I first started.
If you play in play money games, be aware that the players there tend to be far looser and more risk-prone than in cash games because they have made no financial investment. At least observe some cash games so that you don't unconsciously develop the idea that all of your opponents will always play like they don't care.
Also, there is a gigantic variety out there of games, limits, game sizes, money levels, etc. In tournaments you get a huge variety of buyins, tourney sizes, payout structures, starting stack sizes, blind intervals, etc etc etc. Sign up at as many reputable sites as you can and observe the play there to see which sites suit you best.
Before playing to win cash or depositing cash read the site's fine print. There can be extremely arcane requirements for taking your money out.
But the most important advice, for me, is advice I got from a book
. Poker is a game of skill, but it does involve an element of chance, so a hand that is stronger in early play can always get beaten by a weaker hand by the time play ends. This is a so-called "bad beat." Bad beats happen to everyone and can be quite upsetting because they provoke our natural sense of justice. It's almost guaranteed you will be upset by something that happens at a poker table at some point, and, because playing while upset almost always leads to bad losses, you should be prepared to deal with it.
Also, if you're hungry, thirsty, need to go to the bathroom, just had a fight with your spouse, etc., don't play until you have enough experience to deal with these external factors and concentrate on poker.
My rule is that there are no friends at the table. Taking it easy on a fellow player because you like him/her is a bad idea, and actively teaming up with that player to disadvantage other players will get you disciplined by most sites--and, IMO, is morally wrong. Poker is an individual, not a team, game. When it comes to the actual play, everyone at the table is your enemy.
That said, table chat can be fun. I wouldn't do so much of it that it distracts you from your play, but feel free to meet people and make contacts while playing. Never give out sensitive personal information in table chat because it's a public space. So it's okay to say you live in Bujumbura and your first name is Kwame, but not what your email address or phone number is.
Hope the above was helpful. If I've misdirected you in any way, others here will jump all over me.
Mike
As new as they come! 
) so if there are any other questions you have, there are always people around here with the answers and it's a really good place to learn the game.
