The basic combat procedure in Sword & Wizardry is pretty straight forward but a bit vague on specific. This is not an issues as it gives each referee some latitude to customize the combat portion of the game to his taste.
First understand that for over twenty years I played Fantasy Hero, Harnmaster, and GURPS all featuring combat system with a lot of options and a strong use of miniatures. Even when I used AD&D 1st edition I was noted for being a referee that used miniatures.
Since I started running Swords & Wizardry on a regular basis I customized the basic S&W procedures to my taste. Here are some of things I do. Hope you find some of them useful.
1) Everybody rolls individual initiative every round adding their Dexterity Modifier.
2) You can move up to 1/2 of your movement and get your full range of attacks.
3) If you get multiple attacks in melee you get one attack during your initiative and the rest at the end of the round.
4) You can 1/2 move and attack, and attack and 1/2 move.
5) If you have multiple melee attacks you can step on one square before each attack
6) multiple ranged attack all go off on your initiative.
7) you can choose to move up to 1/2 move and split multiple ranged attack at any point on the move.
8) There is not attacks of opportunity or free attacks you can roam the battlefield how you feel like it.
9) The only exception is that you must stop movement when entering a hexes or squares next to a enemy. If you are already next to an enemy you can always take a step of a single hex or square before attacking. This includes multiple attacks.
10) Spells goes at the caster's initiative. If the caster takes damage before their initiative then they can't cast a spell.
11) Take a round to get up if you are knocked prone
12) 1 results in a miss and you throwing your weapon into a really inconvenient spot.
13) 1 while using unarmed combat results in you falling down and going prone
13) a 20 results in a critical hit that is your normal damage + max damage. You can keep rolling and for every 20 you roll you get to add max damage again. For example if Able rolls three 20s in a roll with a longsword and a +1 str modifer then he would do 9+9+9+1d8+1 damage.
14) See the Majestic Wilderlands for various rules on weapons like polearms, crossbows, shields, and mounted combat.
15) attacks from the rear are +2 to hit or flanking a target will grant a +1 to hit to both flankers.