There are a ton of exercises out there...heres my fav though.It involves all four fingers and while it can get boring it DOES get results.


E-----------------------------------------1-2-3-4
B---------------------------------1-2-3-4--------
G-------------------------1-2-3-4----------------
D-----------------1-2-3-4------------------------
A---------1-2-3-4--------------------------------
E-1-2-3-4----------------------------------------


E-3-2-1------------------------------------------
B-------4-3-2-1----------------------------------
G---------------4-3-2-1--------------------------
D------------------------4-3-2-1-----------------
A--------------------------------4-3-2-1---------
E----------------------------------------4-3-2-1-

Simple but effective.Then do it on the next fret.keep going until your do it at the 12th or 15th fret.Then do it in reverse(ascending 4-3-2-1 and descending 1-2-3-4 for example)

Also in the same fashion try ascending 1-3-2-4 and descending 4-2-3-1.

Whatever feels difficult on your fingers,keep at it and alternate pick.A metronome will help keep track of your progress if you write down your current 'speed limit' and break it.

Good luck!You'll be flying in no time!