Don't pick your species randomly
Each alien species requires different skills and perspective to play well. It is important that you find one that matches your play style, both to do well and to have the most fun.
For new players, the Kt'Zr'Kt'Rtl is the easiest to play, followed by the Caylion, Kjasjavikalimm, and finally Faderan. A skilled new player is likely to do well with the Im'dril.
The Eni Et and Unity require very active and pushy trading to do well and tend to be difficult for new players. The Yengii are intended as a challenge for players who have played several games.
Why not Zeth
Playing the Zeth well is more about the player's mindset than experience, so new players who are comfortable being mean can do very well with them.
That said, players who have never played the game before can find them difficult to defend against. So, if most players are experienced and a new player wants to play the Zeth, let them.
Keep the Zeth out of games that are dominated by first time players, though.
When selecting a research team to buy during the bid phase, new players often get bogged down looking at the converters that each will add to the game.
Even for experienced players, the results of a technology are much less important than simply determining whether you can afford the resource cost to invent it.
If you must choose a research team based on what it invents, remember that every player will benefit from that invention.
Don't pick something just because it synergizes well with your own economy, as it likely does the same for everyone. Instead, pick a technology that adds a converter that consumes a resource you overproduce, thus driving up demand for it.
Or, select a technology that tends to produce more of a resource that you desperately need, thus driving up supply. Think about how technologies warp the playing field of the game, not merely what they do for you.