@ express's question:
There are several common leads in Elo, but the point of a lead is to create an advantage, either in LIFE or PILLZ. Usually sound leads have one (or more) of the following properties:
1) Unpredictability. Take a 4 damage card like Gertjan (He's ELO banned, but you get the idea). 0 pilling him is a common play, and if your opponent 0 pills as well, you're up a free 4 damage. Of course, it's only 22 attack, so they COULD 3 pill their 7 power card... but what happens if you throw 1-2 pills on Gertjan? The idea is you're most LIKELY pilling him lightly, but your opponent needs to overpill to avoid a 4 damage. Gertjan is a SAFE, low pill threat in that he almost always forces pills from your opponent, or you get a free 4 damage off.
2) Strong lifegapping. Ector has been mentioned as a strong lead. First, he's a 3*, so he may not be the strongest card in your hand (leading with your nuke is risky, because if your opponent beats it, you're down your best card). Second, he has a whopping DR-resistant 6 damage. AND, he has SOB, which cuts out a lot of attack/power manip and forces your opponent to pill precisely. Third, his damage gives you the threat to pill heavily. Anything from 0-6 pills can be played pretty safely on Ector, depending on your opponents hand, and this unpredictability makes him a strong lead. Leading with Ector (except against SOA) is a safe, reliable lead.
Use these two factors to keep your opponent guessing and maintain the pressure.
Any card can be your lead card. Some 4* cards (Raeth, Tuck, Dr. Falkenstein, Eddie, etc) are excellent leads, and other can be situationally. Basically, you want to ask yourself:
1) Does the card I'm choosing to be a lead have any hard counters (eg. don't lead Sylth Cr or Eddie into SoA, don't lead your biggest damage card if a DR is on the table)?
2) Will I rely on the presence of this card to pressure my opponent (Spyke could be an excellent lead, but he's often better saved as a trump to crush one of your opponent's better cards later on)? If so -- especially if the presence of the card (cough cough Jean) can dictate the turn order, don't lead it, keep it in your hand and lead with a better wall.
3) Does this card provide sufficient threat to my opponent to force pills?
All of these things are signs of a good lead.
Roots is not a bad clan to start the game, since they have SOA, so they can be a safe open. Yookie, Rico, Tuck is all good card to start with, not mentioned Gretchen and Treeman. As badna0 said, the aim is too gain some advantages regardless you play first or not. Advantages can be pills, heal or strategy (like when you have Zhu Tang in your hand but you force your opponent to play his only DR to block Futoshi).