I generally encourage players who are new to competitive chess to worry less about specific opening variations and more about general principles like development, central control, and king safety. However, it is very difficult to avoid questions about specific variations and the most basic of these is "1.e4 or 1.d4?" While I am a firm believer in "play what you like," I think there are good reasons why less experienced players might find they like 1.e4 better.
1.e4 e5 2. Nf3 Nc6.
This position occurs in countless tournament and match games every year between chess at every skill level from woodpusher to International Grandmaster. White has several good options that give Black immediate problems to solve. He can play 3.Bb5 (the Ruy Lopez) threatening to remove the knight that guards Black's e-pawn. He can play 3.Bc4 (the Italian Game) targeting the weak f7 square. After both these moves White is ready to castle. Another popular move is 3.d4 (the Scotch Game) which attacks Black's e-pawn a second time and opens up the game for active piece play.
The positions that arise after 1.e4 e5 are known as the "Open Games" as there is often an early liquidation of the center and open lines for pieces. This is certainly not always the case, however. Some lines in the Ruy Lopez can go twenty moves without a single piece being exchanged. Still, in many lines the players have the option of opening up the position.
1.d4 d5 2. Nc3 Nf6
This position is seen with some frequency on the lower boards in high school matches, however, it becomes much rarer as players become stronger and it is almost never seen in games between masters. Although it looks very similar to the first position, the dynamics are completely different. Unlike the first position, Black's central pawn is defended more times than it is attacked and it is very difficult for White to increase the pressure. White cannot play 3.e4 without losing a pawn. He can prepare e4 with 3.f3 or 3.e3 and 4.Bd3, but the former approach makes king side castling less secure and the latter is time consuming.
The positions after 1.d4 d5 are known as "the Closed Games." There are generally fewer direct threats than in the Open Games and the players have more flexibility in development. There are also less opportunities to open up the game by liquidating the center. This can be frustrating for less experienced who may find themselves slipping into a passive position in which they are unable to come up with a plan.
1. d4 d5 2. c4 e6 3.Nc3 Nf6
This is the Queen's Gambit and it is the way 1.d4 d5 is often handled at the top levels. Chess masters don't play Nc3 without first putting pressure on the Black center with c4. Even so, White still finds it difficult to open the game by forcing the liquidation of the center and White is still four moves away from castling.
The Closed Games are in no way inferior to the Open Games, however, the center tends to remain static until the players have completed their development. Even then, the players often leave the center intact while they expand on one of the wings. This can be disconcerting for the player who is just moving into competitive chess from casual play where they are used to coming to blows much more quickly. I would never want to discourage a player who wanted to try these openings, but it is important to understand how they differ. I might suggest that they start out with something like the Torre Attack rather than the main lines of the Queen's Gambit.
1.d4 d5 2.Nf3 Nf6 3.Bg5 e6 4.e3 Be7 5.Bd3 0-0 6.Nbd2 b6 7.c3 c5.
The Torre Attack is a very sound way to play the Closed Games. Although I have never played it myself, I have faced it several times without particularly good results. White's plan is to leave the central pawn structure intact while he expands on the king side with moves like Ne5 and f4. He plays c3 to fix the pawns in place rather than creating tension with c4. The White knight goes to d2 rather than c3 with the intention of occupying f3 after the other knight moves forward. White's plan is not terribly subtle but it can be very dangerous even for a strong player as can be seen in Rozentalis v. Schneider, Stockholm 1990.