Plotting in R - some ggplot2 tricks

I love to use ggplot2 for plotting in R, but am a beginner, and trying to master it. Here's some things I've learnt recently.

How to plot multiple figures on one plot
I got some hints from stackoverflow. Here's a rough example of a multi-plot with 6 plots, in 2 columns and 3 rows:
require(gridExtra)
library(ggplot2)
# make 6 plots and save as myplot_1, ... myplot_6
# make final plot:
grid.arrange(myplot1,myplot2,myplot3,myplot4,myplot5,myplot6,ncol=2)

How to change the angle of x-labels for the boxes in a boxplot
Something like this: (angle changes the angle, size changes the size of the text)
myplot <- myplot + geom_boxplot(outlier.size = 2, fill="red") + ylab("% Repeat") + xlab("Clade") + theme(axis.text.x=element_text(angle=-25,size=7))

Add a title to the plot:
Something like this: (use 'ggtitle')
myplot <- myplot + geom_boxplot(outlier.size = 2, fill="red") + ylab("% Repeat") + xlab("Clade") + theme(axis.text.x=element_text(angle=-25,size=7)) + ggtitle("Unknown repeats")

Change colour of boxes in boxplot:
Something like this: (note: put aes(fill=myxorder) in the ggplot command rather than the geom_boxplot command)
myplot <- ggplot(data = mydata_b, aes(myxorder, myvalues_b, fill=myxorder))
myplot <- myplot + geom_boxplot(outlier.size = 2) + ylab("% Repeat") + xlab("Clade") + scale_fill_manual(values=c("red","pink","green","blue","yellow","orange","purple"))
You can remove the legend made using:
..."orange","purple")) + guides(fill=FALSE)

Put the x-axis title closer to the plot:
Something like this: (use theme=axis.title.x)
myplot <- ggplot(data = mydata_b, aes(myxorder, myvalues_b))
myplot <- myplot + geom_boxplot(outlier.size = 2, fill="red") + ylab("% Repeat") + xlab("Clade") + theme(axis.title.x=element_text(vjust=2.0))