Attributes: You will have 6/4/3 starting dots, to spend in three categories (Physical/Social/Mental) in whatever order most suits your PC (Primary/Secondary/Tertiary). Give thought to spending them according to the kind of person your character is, not what looks neat or what you think you have to have to keep from being killed.
Abilities (Talents/Skills/Knowledges): You will have 11/7/4 starting dots. You may not have anything above 3 dots in Initial Stage here.
Tactics - Cells do not start with tactics and must learn them in game.
Remember that a tactic hinges on being utilized by a cell working as a well oiled machine. If you buy Corral in game and hook into a cell that knows Corral, the cell still needs to practice together to work out any kinks that could end someone's Vigil in the field.
Hunters work best in cells, knowing each other so that they can learn Tactics and work towards accomplishing thier goals. Enter with a clear grasp of your Hunter's tier ( and if they're a second level tier, which conspiracy they follow ) and thier Profession so that you can gravitate towards joining a cell and know what they can offer that cell. You should be actively seeking a cell to join immediately upon approval and you are encouraged to bring your friends and thier characters if you want to form a cell together.
There are no limits on cell size besides those listed on p. 30 of the Vigil. I do want to make it clear that while you are welcome to have a large cell and there will certainly be exceptions here and there, there will be no 10 wo/man death squads.