Does anyone know of exercises that improve the traditional plucking method? I use the first and middle fingers on my right hand. I would like to increase speed and dexterity. Thank you.

Hi jjvb, welcome to our little forum,
Most new players need to exercise the left (fretting) hand. It is usually week, particulaly the little finger. The right hand/fingers, is usually not a strength problem. The best exercise is playing, in my opinion. You can use just one string or two strings and walk your fingers, alternating and trying to have the same stroke/touch/attack, balanced on each finger.
Rocky

Yes, for beginners who may not yet have much fretting dexterity plucking an open string can help develop plucking dexterity.

Once you have some fretting proficiency you can play anything, but scales are often used out of convenience.

I like the C major scale but use whatever you like. Play up and down the scale in quarter notes, alternating plucking fingers as you go. Then play two eighth notes per scale tone (C C D D E E ...). Then try three triplets per scale tone, and even four sixteenths.

For some variety play the scale in thirds, e.g. C E D F E G F A G B A C. You can also play the thirds going down: C A B G A F G E F D E C (I usually add D B C).

You can also mix and match. Play the scale going up and thirds coming down. This is my favorite (combined with triplets).

Practice with a metronome. Start at a comfortably slow tempo. Slowly increase tempo over time as dexterity improves.

I'm not sure of your progress but something else that is very important is the angle of your fingers across the strings. Avoid plucking upward on the strings. Your two fingers should slide across the strings and land on the string above, (except for the top string) Alternate plucking with the two fingers in time to a metronome is a good idea.
Rocky