In this article I am going to describe some of the ways from which you can reduce your time required for solving a 3X3X3 Rubik's Cube. This page includes some by video tutorials by some cubists taken from YouTube which will help you with the process. First, I assume that you already know the way to solve the cube with the beginners method. SO here are the steps:
1. Quality Cube: The main thing required to solve the cube fast is to have a Rubik's cube that spins faster. So I recommend you to buy a good and original rubik's cube that is easy to rotate and use.
2. Lubrication: If you have a cube that don't spin faster then you have to probably lubricate it before it does so. Lubrication means popping out the cubies and applying some lubricating material like silicone spray or cube lube etc. so that the cube spins faster. Petroleum Jelly(Vaseline) is also applied by it is not recommended. Here is a video which shows the way how to do lubricate your cube:
3. Solving the (white) cross faster: Now you have a cube that spins faster you have to start learning the method in which you can solve the cross in as few moves as possible. It is known that any cross can be solved in 8 moves or less. So by observing the cube and intuitively learning how to solve the cross in fewer moves you can reduce the time required for the overall solve.
4. Fridrich Method for F2L: By learning the Fridrich method for solving the First two layers(F2L) you can reduce the time by constructing the bottom 2 layers simultaneously instead of one by one. This method has many combinations but can be learnt by practising several times. A video on that:
5. OLL and PLL: Instead of the standard beginners method (which involves fewer algorithms) you can learn the OLL and PLL algorithms which will Orient the last layer(OLL) and Permute the Last Layer(PLL) with very less moves as compared to beginner's method. But learning many algorithms (57 + 21 = 78 in total!!) is not easy. So you can at least practise the "Two Look" OLL and PLL(described in the following video) to do it quicker that the begginer's method.
opposite edges: F (R U R' U') F'
adjacent edges: f (R U R' U') f'
all edges: [F (R U R' U') F'] [f (R U R' U') f']
Anti-Sune: (R' U' R) U' (R' U2 R)
Sune: (R U R') U (R U2 R')
Cross Symmetric: F (R U R' U') (R U R' U') (R U R' U') F'
Cross not symmetric: (R U2) (R2 U') (R2 U') (R2 U2 R)
-----------------or: [f (R U R' U') f'] [F (R U R' U') F']
Headlights: (R2' D) (R' U2) (R D') (R' U2 R')
Chameleon: (r U R' U') (r' F R F')
Diagonal Corners orient: F' (r U R' U') r' F R
Algorithms (in order):
1. x [(R' U R') D2] [(R U' R') D2] R2
2. R2 U [R U R' U'] (R' U') (R' U R')
3. [R U'] [R U] [R U] [R U'] R' U' R2
4. M2 U M2 U2 M2 U M2
5. M2 U M2 U M' U2 M2 U2 M' U2
6. x' [(R U' R') D (R U R')] u2 [(R' U R) D (R' U' R)]