This guide covers Risk Strategy based on the standard rules. You can check them out here if you need a refresher.
The overall approach to the game
Lose the defensive mindset
Risk is the game of attacking and effective use of your armies. The person who wins is the one who is able to grow and quickly use their armies. To do this, you need to think of attacking and not hoarding.
Stay ahead of the army build-up race
What is a good strategy for Risk? It is to always stay ahead of the army build-up race. Conquer territories and continents to gain bonus armies! However, it is not only about you! You need to to stop others from doing the same. If you have an opportunity to stop your opponents from controlling continents and gaining bonus units, you should always act on it.
Early game set-up strategy
Awareness of your territories and its neighbours
If you have a territory that is not as connected to your opponents, use it to form your base.
Distribute your armies effectively
If a territory (Australia, Madagascar) is relatively isolated and is behind other territories you own , don’t waste putting too many armies on them.
Understand the odds
Probability of attacker winning
The attacker has a better chance of winning when it has more dice. So, attack with larger numbers as you will have more dice.
The attacker is at a statistical disadvantage only when it is attacking with 5 armies or less. So, attack as soon as possible when you get the chance as you have the advantage.
Territorial and Continent Advantage
North America provides the most attractive ratio of continent bonus armies per territory controlled.
You can attack Africa easily but it is pretty difficult to defend.
Australia is boxed in. While it is not as connected, you will need to devote armies to make sure that you defend it well.
Deciding who to eliminate in Risk
Reinforce your attacks by gaining eliminated opponent Risk cards
When you eliminate an opponent, you get their Risk cards. When you get more than 6 Risk cards, you have to immediately exchange them for armies. These armies can reinforce and support additional attacks in your turn. Factor this when deciding who to attack first.