So just to clarify, what do you do for last layer now? There is no "standard beginner's method", so what you do might be different than what I, and other posters, are thinking of.
Most people are pointing you to learn 4LLL, which I recommend as well. Learning 4LLL consists of 16 algorithms, some of which you certainly already know. Typically 4LLL is split up into 2-look OLL and 2-look PLL, where you first orient all the last layer edges to form the yellow (if you start on white) cross, then orient the corners to make a yellow face, then permute the corners, then permute the edges to solve the cube.
First you orient edges and make a yellow cross using one of 3 algorithms -
F (R U R' U') F'
// "L case" - F sexy F'
F (U R U' R') F'
// "Line" - F inverse sexy F'
F (R U R' U') F' f (R U R' U') f'
// "Dot" - F sexy F' f sexy f'
Then you orient corners to make a yellow face using one of 7 algorithms -
R U R' U R U2 R'
// "Sune"
R' U' R U' R' U2 R
// "Backsune" or Antisune
R U R' U (R U' R' U) R U2 R'
// "Doublesune" or H - Sune twice
R U2' R2' U' R2 U' R2' U2' R
// "Pi" or "The Wheel" - note the 's on R2' / U2'
R U R' U R U2' R2' U' R U' R' U2 R
// "Headlights" or U - Sune then Backsune
r U R' U' r' F R F'
// "T" - fat sexy then fat sledgehammer
F' r U R' U' r' F R
// "L" or "Bowtie" - same as "T" but with the F' as the first move, instead of last.
Then you permute corners to leave only edges using one of 2 algorithms -
(R U R' U') R' F R2 U' R' U' R U R' F'
// T Perm, swaps the two right side corners
F (R U' R' U' R U R') F' (R U R' U') (R' F R F')
// Y Perm, swaps diagonal corners
Then you permute edges and solve the cube using one of 4 algorithms -
R2 U (R U R' U') R' U' R' U R' // Ub Perm - clockwise cycle of 3 edges
R U' R U R (U R U' R') U' R2 // Ua Perm - counterclockwise cycle
M2 U' M2 U2' M2 U' M2 // H perm
M' U' M2 U' M2 U' M' U2 M2 // Z perm
Alright I don't know why I chose to go to such great effort there to do that but once I got started I didn't want to not finish it. Those are the algs I would recommend learning when learning 4LLL for the first time. You probably know some of them already, or you may know other algs to solve some of the same cases. More info can be found on the Wiki
Good luck