I have said this in the general advice for all armies but it does need saying again:-
Get The Rule Books and Read Them!
You will need the main Warhammer 40k Rule Book, and the Codex: Space Marines for the Space Marine specific rules.
Sharing rule books with friends might work for a week or two, until you decide whether you like the game or not. After that you do need the books. If you have to decide between spending money on the rule books or on models get the books. Use Plasticine / coins / used match sticks / silver foil, to make some home made models. If you have models with out the rules then they will just sit on a shelf looking pretty.
<img class="alignleft size-full wp-image-229" src="http://wargametactics.com/wp-content/uploads/2014/11/40k-Space-Marine-Tactical-Squad-150.jpg" alt="A WH40k Space Marine Tactical Squad " width="150" height="112" />Learn how to use the Space Marine Tactical Squads in your army, and everything else will fall in to place. Learn when to stand your ground, when to advance and when to retreat. If you learn these three skill with this one squad type you will win 60% to 70% of the games you play.
>Also see: Space Marine Troop Tactics
As a new player keep your army simple. Four tactical Squads and one HQ. choice is all that you require of the first few games.
It won’t take you long to spot that different Space Marine players have different styles of playing. Some will charge forward and get in to close assault as soon as possible, others will stand as far back as possible and use their guns to whittle down the advancing enemy. Other players will use fast troops and vehicles to wage a hit-and-run style campaign, and some prefer a close ranged fire fight. In this section I will be examining different playing styles and the pros and cons of each.
<img class="alignright size-full wp-image-198" src="http://wargametactics.com/wp-content/uploads/2014/11/40k-Space-Marine-Assault-Squads-150.jpg" alt="Space Marine unit with jet packs" width="150" height="112" />Close Assault armies are very successful. They are so successful that Games Workshop have changes the assault rules to weaken them a notch or two. The reason that they are so good is that you have two assault rounds each turn and only one shooting turn (your assault phase, and the opponents assault phase). Some of the issues that a close assault army has are speed, grouping, and cover.
With a close assault army speed is of the essence. The sooner you are in combat the sooner you will be using your killing skills. Speed can be achieved by putting jet-packs to the back of your troops, putting then in transport, or dropping them on to the battle field with drop pods and teleport.
With assaults it is much better to attack a weak defence with a much larger force. To do this you need to identify a weak spot in the defence and hit it with all your army. That requires all your army to arrive at the same time. If your troops arrive in a piece-meal fashion then your opponent will be able to hack you down before you reach critical mass.
To effective assaulting force you need to reach the target in one piece. This means that you have to avoid being shot at. Cover has several different forms. Buildings and hard cover that you can run up behind reducing the number of shots that the enemy can take at you.
Tanks can provide moving cover for the troops inside them, and any troops that follow them.
Your opponent will use cover to protect his troops. This allows him to attack first when he is assaulted, probably killing some of your troops before they can strike back. This advantage can be minimized by taking frag grenades.
> Also See: Warhammer 40k Close Assault Tactics
The Space Marines are a great army for a player to start with when they are starting to learn to play Warhammer 40k. The question I am often asked is what type / style of army should a starting player choose, and which models should they get.