If you want actual helpful guidelines on writing, skip to the last paragraph -- the link's there. I'm not in a position to lecture. If you're bored or have nothing else to do, read on.
Writers are a diverse bunch. Simply saying you're a writer could mean a lot of things: do you write novels? Plays? Short stories? Essays? Columns? Poems? Speeches? News? The list goes on. The written word is a medium and one that has many applications.
Exposition done, I'll talk about me. When I decided to sign up for Creative Writing as my undergraduate degree, I wanted to create stories. (By the way, don't let what "you took up in college" confuse you: your undergraduate degree is just a guide. Your career is what you make of it. There are people who took up Management only to be a well-known writer later on and there are people in the Humanities who end up as successful businessmen. Heck, there are people who didn't even finish high school and are CEO's of various companies.) Unfortunately, while I will go as to arrogantly say I have a talent in writing, my talent doesn't necessarily extend to fiction.
I'll be frank with you: I'm better at telling rather than showing. Perhaps that's why you're reading this blog entry in the first place. I'm not creating mood or showing you a vivid scene from my childhood, I'm telling it to you flat-out. That's my natural disposition towards writing. Which doesn't necessarily make me a bad writer but certain fields of writing suit me better than others.
If I were to rank my "writing skills", they'd follow this heirarchy:
1) Blogging. (Not a real "writing skill" yet because blogging has no fixed form as of yet. It's too easy, too fluid. Although maintaining a compelling blog takes skill.)
2) Essay writing. (In a way, my blog entries are really essays. So maybe #1 and #2 is really just the same, at least in my case.)
3) Feature writing. (Although it's a writing skill I haven't "exercised" lately.)
4) Fiction. (Which is to say I suck at it.)
5) Poetry. (If I suck at fiction, I have no ear for poetry.)
Perhaps some skills I'll manage to sneak in after #3 but before #4. Or maybe there are some things I'm worse at than fiction (such as writing a comic script for example). But you get my point.
Of course even fiction has many factors. The horror writer H.P. Lovecraft, for example, was great at setting the mood and evoking terror. He was horrible with dialogue however but that didn't stop him from being one of the recognized writers of the 20th century.
As for me, I suck at dialogue too. Or rather banter between characters. I was exposed to crappy Tom Swift books as a kid and they used adverbs extensively. Including in dialogue. You known the likes of "he quickly said", "he angrily shouted", "he stuttered", etc. These are things I should avoid and up until recently, I didn't really know how to solve. There's also the fact that synonyms aren't -- they're close approximation of the original word but they're not the same. In Japanese, the word Watashi might sound similar to Boku but anyone who's familiar with the language will know there is a subtle but significant difference between the two. In Tagalog, it might be the words kuya and kapatid. In English, scion and descendant, son and heir. Close but not quite.
Oh, as for the helpful tip, check out the writing guidelines from Weird Tales magazine. (It's in PDF!) I got the realization from the previous paragraph based on their writing guidelines (which is fun and entertaining, and doubles as an exam for proofing/editing).