Everybody has different tastes and preferences. I like to encourage my students to experiment and find out what works for them. Here are a few guidelines to help you:
Electric Guitar Strings: Strings come in sets such as 8's, 9's, 10's etc... in general I would recommend 9's. Overall 9's are a good place to start. I would especially recommend these for someone who doesn't know what they want. By the way, 9's refer to the gauge or the thickness of the string. There are all types of brands of strings and in my opinion all are pretty good I mean to say its pretty hard to make a crappy string. I prefer the brand Ernie Ball. In trying to find what works for me, I settled on 10's. I have small hands and 11's are a little too much for me. The general idea is that the thicker the gauge the fatter the tone, however thicker gauge strings are harder to play on, and also harder to bend. Ultimately, its a toss-up. You have to decide what kind of music you want to play and what type of tone you want to have. For heavy metal, you might want to try heavy gauge strings because they tend to be good for tuning low. The general rule for this is: "for lower tunings use heavier gauged strings" For country lead, you would probably want a light gauge such as 9's or 10's in order to get that chicken pickin', twangy, country sound. These guidelines aren't set in stone, but they are what most professional players do. Overall, you have to figure out what works for you.
For acoustic guitar strings I personally wouldnt use any set lower than 11's. When dealing with acoustic guitars one generally wants to use a higher gauge string set than they would on an electric guitar because thinner gauges on acoustic guitars do not resonate as well nor sound as pronounced. That is thinner gauges on an acoustic guitar sound, well, thinner. (pun intended)
For picks I like to use Dunlop Tortex .88mm sharp. I encourage you to experiment and see what works for you, picks are cheap so go and get a variety of them. Try different thickness's and shapes. I like to use thick picks because they do not bend. I don't like them to bend because its harder to control. To me thin picks give a boingy sound. I read this in an issue of guitar player and found that I agreed with this.