Flat picking is an art, contrary to what some classical folks think
To be good at it takes a ton of practice and a bit of thinking before it comes naturally.
The first thing with picking is you almost always want to use alternate picking. About the only time you don’t want to use it is when you are doing some pedal tone stuff. An example would be some metal riffs, like Metallica.
There are a ton of exercises out there. The first ones you want to do are simple scales using alternate picking all the time. Up then down all the time. Start with three notes per string and also do pentatonic scales. The next step is string skipping using the same scales with alternate picking. Then move on to arpeggios. Arpeggios are, for me at least, the hardest to pick correctly. It is easy to cheat, sweep pick, etc. When doing arpeggio practice, always alternate and start with short three string exercises. Once you get those down start extending the arpeggios until you are moving across all six strings. Always use alternate picking.Start slow with a metronome. Make sure you can do it smoothly and mistake free. Once you get that down, increase the speed in steps until you lose it. Lather, rinse, repeat daily.
The biggest issue most players I know have with picking is laziness. It is easier to pick the initial note and either hammer on or pull off the rest, especially when playing fast. Hammer ons and pull offs are useful but you get a different tone and feel than when you pick. When working on picking never do hammer ons or pull offs. Pick every note. For a lot of players it takes a while to get used to picking everything.
There are some other things to think about. First, when you are first working on alternate picking you want to think about which stroke to start on, up or down. After a while it will become natural and you’ll start with the correct stroke but when practicing start with both. Also, when string skipping and doing arpeggios, make sure you alternate. String skipping exercises are great for accuracy. An example
-----------------------------------------------------------------5–7–8-
------------------------------------------------5–7–8-------------------
------------------------------4–5–7--------------------4–5–7----------
-----------4–5–7---------------------4–5–7----------------------------
--------------------3–5–7-----------------------------------------------
–3–5–7----------------------------------------------------------------
Pick direction
–u–d–u–>
and
–d–u–d–>
Probably the most frustrating exercise for me is alternate picking arepeggios with one note per string. It takes a while to become proficent at it and it requires more hand movement than doing just scales. Your hand will be moving as you pick so that your hand is positioned over the string you are picking. Doing one note per string gets you used to moving your hand.
A couple things to avoid. First make sure you work on each string and get used to moving your hand. I know a lot of metal heads who are great at alternate picking on the low E and the A but once they get higher than that it falls apart. The reason is they get used to an anchor position with their hand on the bridge. Anchoring your hand with your pinkie is very common but you can also fall into the same trap where moving up to higher strings causes issues. I anchor but it moves with my hand, sometimes my pinkie is on the high e, other times it is on the body of the guitar.
Last, when you are playing an actual piece, run through it slow at first and think about which way the pick should be going for each note. Sometimes you come across pieces where you want to start on an up stroke because it will make part of the piece easier later on. I often change neck positions or picking strokes for certain parts to make the picking more efficient.
If you want more exercises, PM me and I’ll email you some.
Slee
On a side note, my fingerpicking isn’t all that great. I can get by with it and want to improve my skills yet there isn’t quite enough time to work on evertyhing. I respect the heck out of the classical guys and gals who have it mastered, along with the chicken pickin folks.