Building a sideboard

[Crisys]

I just started playing magic about 3 months ago.  Now I want to start playing competitive, at least being competitive at my lgs FNM. 

I'm playing Gruul aggro which I understand isn't super competive and can be stopped, but the side board is what really gets me.  I see some sideboards that have 1 copy of a card. 

Is this effective?  How often are you going to actually draw that card.  My deck has 4 of every card in it except for 4 cards.  And my sideboard only has 5 different cards, 3 of each card.  I think the way I'm doing it works but I just want opinions and insight from seasoned players.  I want to step my game up to the next level and effective side boarding is a weakness for me I would say.

[Kaleo42]

Sideboards being only 15 cards is a huge restriction that doesnt always allow for 3s and 4s. Sure 3 ofs and 4 ofs ensure you'll see them more often, but some things you dont want to see more often. {Witchbane orb} for example is good to put in against certain decks but is terrible to draw when you already have one in play. You have to weigh it's effectiveness if you were to pull all copies at once when deciding how many to board.