HC Advice
As HC you need to look at every angle and ideally have 2 other HC around you that you can play devils advocate with. Of course, you need to be able to come to quick and positive decisions. Having HC who specialise in certains area's may help work ethic.
Goals
Plan and plan some more for all the main area's of the alliance and try to have some direction for the alliance. What do you want to achieve? Just aiming for #1 alliance isnt good enough, not only will this likely provide false promises to keen members but it will deflate any energy to progress.
Spirit
Be realistic but optimistic and NEVER look down on your members, you must work hard to be best friends with all members. Bond with them and they will in turn bond with the alliance. It only takes 10 loyal members to open up recruitment through their network of contacts through a round. A strong spirit will also benifit activity, this being THE key aspect for PA success.
Promotion & Alliance Theme
A number of replys comment on promotion and marketting of your alliance, while i think this is important i dont think you should start this until alliance foundations are stable (active command staff, organised military). Experienced players will see right through a newer alliances publicity and they will not be attracted to it.
If you have yet to set your alliance in motion, then take time to figure out such things as alliance name & theme. Try to choose something that is original (the Wolf theme has been murdered goddamit;P) and will inspire and ignite the imaginations of your members, this can be useful when motivating members at times of war.
Just some extra thoughts
Woof!