Another easy thing to do is remove the battery and then remove the tray underneath, then look,around for 2 black earth leads. Take these off and wire brush or sandpaper the connections. Also worth giving your battery lead clamps a clean up, positive and negative.
I was having problems with the key just clicking and therefore car not starting. It's early days yet, but I cleaned mine up 9 days ago and my Wife says the car has started 1st time everytime. Well worth getting a 10mm and 13mm socket out and spending 30 mins, at least you can tick it off the list.
GT 3.2 V6 - Q2, KONI FSD & EIBACH PROKIT, GTA REMAP, MICHELLIN PS3's, BMC CDA
159 SW 2.4JTDM TI - ALFATUNED, WIZARD BACK BOXES, KW V3 COILOVERS, NOKIAN WR A3/MICHELLIN PS3, PCA DYNAMICS ALIGNMENT.