Fed is usually is the best choice of inital faction since most people play it anyway. They have the biggest fleets (guilds) and have the biggest selection of ships. Not that it matters since you can fly any ship from any faction, at any level.
There are 3 Feds you can do. Normal, TOS era and Discovery era. The real difference is starting ship, the tutorial, and the TOS stuff has a short bit of standalone missions. Disco and TOS feds get send to the modern era almost immediately.
You could try a Klingon, as I think there's still a recruitment event going on (so free stuff). They're generally a bit harder, but very, VERY Klingon. And by a bit I mean some of their early missions aren't really balanced for level 1 characters to play, but you do it anyway. They have fewer fleets to join.
Romulan has the best faction storyline, but have to pick to ally with the Feds ore Klinks and getting access to their hubs and ships and bridge officers. And ships, but again. . .
Jem'hadar are also an option. You start at level 60, get thrown into one of the best storylines in the game (that everyone gets), and has one of the more badass intros in the game. But you also have to choose an ally like the Romulans, there's almost nothing unique to them, and you can ONLY pley a Jem, no other Dominion races.
You will get access to everything, eventually, except the faction only missions, which aren't the main thing anymore. Hell you can fly any ship at any point, even the fancy Tier 6 ships can be flown by a new player right out the gate (with some temporarily reduced stats).
As for species or career, pick whatever. Species doesn't have THAT much influence, though the Alien selection lets you build your own and have extra traits. Career has more of influence on ground combat, but even then there are a lot of ways to play. In space, you get different special powers but you can play anyway you want. Though the role of healer doesn't really exist. I mean you COULD do it, but heals work better on YOURSELF than anyone else. Science career is supposed to be a kind of healer class, but on ground it's much better as a tank, while in space it's all about the space magic (all hail Gravity Well).
It's an easy game, really. Death has virtually no penalty (unless you crank up the difficulty), you can choose when to engage, you have targets, er, Bridge officers who can do a lot of the fighting (btw, "y" will make them all attack your current target), and there's not time limit on most things. Heck there are whole systems in place that will allow you to level up to max and practically never fire a shot.
Oh, you will kill a lot of NPCs. Just be ready for that. Fed, Klink, Rom, whatever, you have a craving for blood that can not be extinquished. Kill, kill, KILL THEM ALL!
And if you need help just ask.