Each side begins the game with the ability to place Influence in Europe. (Note that this is Influence, not Operations points for influence.) The USSR can place up to 6 in Eastern Europe, while the US can place 7 in Western Europe.
The standard opening setup for the USSR is 4 East Germany, 4 Poland, 1 Yugoslavia. There is rarely any reason to deviate from this setup. As USSR, you overcontrol your two battleground countries, vulnerable to East European Unrest and Mid/Late War events. Your 1 influence in Yugoslavia provides you with access to Italy, keeping your options open, as well as Greece. Occasionally, you will see people play into Bulgaria, as it also provides access to Greece and is the only Eastern European country inaccessible from the rest of Eastern Europe. But it does not provide access to Italy.
Alternatively, the “Comecon Trap” setup is 3 East Germany, 4 Austria, 2 Yugoslavia. You headline Comecon, gaining you control of Austria and Yugoslavia. (You can also do this with Warsaw Pact Formed, but Warsaw Pact is a critical card for the USSR in the Late War.) On AR1 of Turn 1, you are now able to realign West Germany and Italy at +1. Against a standard US setup, if you are successful, you can obliterate the US position in Europe in a single play. However, this gambit is risky: not only are you not couping Iran (thereby allowing US unfettered access to western Asia), but it can be easily thwarted by a US headline of Defectors, Truman Doctrine (if they played enough into Austria), Duck and Cover, or even Marshall Plan.
The standard opening setup for the US is 4 West Germany, 3 Italy. As USA, you take the two safest battlegrounds in Western Europe, and the overcontrol of Italy guards against a Socialist Governments headline and/or T1 Italy coup.
If you have Marshall Plan in your opening hand and plan to headline it, you can open with 3 West Germany, 2 Italy, 1 Greece, 1 Turkey. You still end up with the same 4/3 in West Germany and Italy, but you get two of the three critical Mediterranean non-battleground countries (the only two that the USSR has easy access to) and make it very difficult for the USSR to ever score Domination against you.
There are several reasons why you may want to leave West Germany empty. For example, you fear Red Scare/Purge + Blockade, when you have no cards to discard, or alternatively, you hold both Blockade and De-Stalinization in hand and want to play Blockade without discarding any card this turn (so that you can hold De-Stal through the reshuffle). In such situations (assuming you lack Marshall Plan), you can open with 4 Italy, 1 Greece, 1 Austria, 1 Turkey. This guards Italy against Socialist Governments followed by a coup or Duck & Cover, provides an additional adjacency to Italy in case Socialist Governments removes adjacency to Italy and you get couped out, and provides access to West Germany so that you can threaten to take it immediately.