1. Initial setup (happens only once for any given combat):
All roll 2d6 as individuals and add their DEX bonus if any. If any side has someone with Tactics skill, they can make a skill check and if successful, the Effect can be added to everyones' initiative for the relevant side. Only one character (the one with the highest Tactics skill) makes the roll.
2. Progression:
If you nominate to act hastily, you ADD 1 to your initiative but take a -1 penalty to all your actions that round.
Order final initiative scores for all characters (i.e., for both sides) from highest to lowest.
Highest acts first.
If there are any draws, the character with the highest DEX goes first.
If their DEX are equal, actions are simultaneous.
Carry out actions and resolve effects of them.
If you choose to wait and do nothing in round X round, you return to step 2. at the start of round X+1 but automatically beat everyone else. I suppose if two or more people opt to do this, you then resolve who goes first by the highest DEX rule above (this point is not detailed in the rules).
If someone has Leadership skill, they can take their major action to do a Leadership skill check. If successful, the effect is ADDED to the initiative of one individual in round X+1. I assume you can't inspire yourself, although this is not detailed in the rules.
If you use a weapon, compare your STR modifier to the heft/recoil number. If your STR modifier is less than the heft/recoil number, SUBTRACT the absolute difference from your initiative roll for round X+1 . There is more recoil if you fire on semi- or full-automatic.
If you react by dodging or parrying, SUBTRACT 2 from your initiative roll for round X+1 for each such action you do this round. Also, subtract 1 from skill checks in round X+1. Initative and skill check penalties are cumulative.
Thus, there are some things you do in round X that can increase your initiative in round X+1 (waiting, Leadership) while there are some things you do in round X that may decrease your initiative in round X+1 (e.g., reacting, using weapons). These effects to your initiative do not carry over further than round X+1, but of course what you do in X+1 may carry over to round X+2. At the start of every round you roll 2d6 again and add DEX bonus plus these carry-over modifiers.
