Now that you've read about general strategy for many pages lets talk about something easier to absorb, like what heroes are good for new players.
All heroes in Dota take a lot of finesse to play them well, but some have very straight forward abilities and play styles that will help a new player play them well.
This first group of heroes are loosely defined as carries. They are strong in the mid and late game due to high damage output from items and skill synergy, but they are somewhat weak in the early game.
CARRY HEROES
SVEN
WRAITH KING
JUGGERNAUT
SNIPER
RAZOR
PHANTOM ASSASSIN
VIPER
This next group of heroes are pretty easy to play, and most of them are played in a solo role since they become strong once they get their ultimate's at level 6. It's fine to dual lane these too if you have to.
SOLO HEROES
BLOODSEEKER
CENTAUR
AXE
PUDGE
TIDEHUNTER
ZEUS
SPIRIT BREAKER
This last batch of heroes are the easiest to play support heroes in the game. They have very straight forward abilities that won't take you long to understand when playing them for your first time.
SUPPORT HEROES
VENGEFUL SPIRIT
CRYSTAL MAIDEN
OGRE MAGI
WITCH DOCTOR
LICH
LION
WARLOCK
There are also a couple heroes in Dota 2 that I think are too complicated for a brand new player to attempt, unless obscurity suits the way that you like to express yourself in video games. Most of these heroes take a LOT of practice to play because of they don't have the typical skill layout.
Invoker, for example, uses a combination of three buttons called orbs to prepare a spell to be cast, so to cast Tornado, you have to first press Q, then W, then W, and then R, which prepares you to use Tornado. He has 8 other spells with button combinations, and it's easy to forget them in battle.
Another example is Meepo, and Chen. These heroes control more than 3 units on average, and each one can move by themselves which is very overwhelming for all players if you don't practice it.
And finally, some of these heroes just require a large amount of game knowledge to play properly. If you don't have that game knowledge yet, the heroes are going to feel underpowered, so I'd recommend steering clear until you feel a little comfortable with the game.
For that reason, I don't recommend starting Dota on any of these heroes, but once you have the basics of the game, poke your head through and see if they sound fun.
AVOID IF YOU SUCK AT DOTA, MICRO, OR PRESSING BUTTONS RAPIDLY
EARTH SPIRIT
LONE DRUID
BROODMOTHER
MEEPO
TINKER
ENCHANTRESS
CHEN
ORACLE
IO
SHADOW DEMON
INVOKER
WINTER WYVERN
VISAGE
NAGA SIREN
TERRORBLADE
TECHIES
If you want to read about any of these heroes and their skills or stats