Picks come gauged in many different thicknesses. Most common are the three basics: thin, medium and heavy. Picks also come in several different sizes and shapes. Buy a handful of all the different kinds at your favorite music store and find the one that’s just right for you!! Most beginners start with the thinner picks and it seems many experienced players move towards the heavier picks. But that’s just a generalization, you may find that you start with heavy picks and grow into lights. Remember, there is not one pick that is the best!! This is a very personal matter, between you and your guitar.
Fingerpicks are neat, too. Again, try them all. What seems most common are metal fingerpicks used in conjunction with plastic thumb picks.
Capos are one of the neatest things ever invented for the guitar. The idea behind the capo is to let you play in other keys without having to learn new chords. For example, if you know a song with the chords G, C, and D, but find that it is a little low for you to sing (in other words, you feel it would sound better if you could sing it a bit higher in pitch), then try a capo. With a capo, all you need to do is place the capo, say on the second fret, and then play your chords (G,C,D) just like before. What you have done is raised the pitch (you are now really playing A,D,E), but without having to figure out new chords.
That’s what the capo was made for, but guess what, it’s really neat for other reasons. Try putting the capo on the 7th fret! Play your G,C,D. Listen to the quality of the chords. You could never get chords to sound this bright played at their regular open position. You can use this to get great new sounds for some old boring chords. Experiment!!
Some capos are called half or “partial” capos, which allow you to just capo a few strings at a time thus in effect giving you an open tuning… I love these, check out Shubb brand capos for these!
There is even a company that makes a capo that lets you capo individual strings, called Third Hand Capos. This allows you to build “open tunings” without having to retune the guitar. These are great fun, check them out.