I can answer with a question: what do leaders do?
- They help to plan actions of the group and execute these plans.
- They react for changing situation and help to deal with unexpected.
- They delegate responsibility and power according to individual predispositions.
- They defend the group.
- They make others willing to follow them.
Basically the best way to become an effective project leader is to show leadership in practice. If you start from nothing probably at the beginning you need small steps. No one would believe in your huge plan designed up-front until you prove that you can successfully plan a small thing. No one would believe you can carry the team through big problems until they learn you're dealing with everyday small issues flawlessly.
Basically a leader is a person who helps the rest of the team shine. It means they can use a potential of the team, i.e. find the right place for everyone, give them enough power to execute their tasks, give them enough freedom, etc. At the same time the leader tries to keep conditions possibly close to ideal for the team, i.e. defending the team from unfair attacks or destroying optimal work environment, isolating them from unnecessary buzz, removing obstacles all over the way, etc.
With such attitude people start considering a person someone they know they can count on whenever a tough time comes and someone they want to have around. They're willing to follow such leader.