If you're going into downtown Manhattan from LGA, you can spend (I think) $2.50 to take the M60 bus along Astoria Blvd. bus to the stop at 31st St. for transfers to the N, 125th & Lexington for the 4/5/6, 125th & Lenox for the 2/3, or 125th & St. Nicholas for the A/C/D (the first stop is in Astoria, Queens; the last 3 stops are in Harlem, Manhattan)...
or you can spend the same $2.50 and take the Q33 or Q47 to their terminus, the 74th Street bus stop in Jackson Heights, and walk a short distance to transfer to the 7 or E/F/R...
or you can spend $12 and take a one-way shuttle bus direct to Grand Central Station.
After many years of being too cheap to take the shuttle, I am now a NYAS
devotee. fork a bunch of transfers while I'm hauling around a giant backpack. If you'd prefer to do the bus/subway thing, I highly recommend getting off at 125th and Lex for the 4/5/6 because it will, if you so desire, spit you out right at Grand Central or Union Station, from which you can find basically any public transit route to anywhere.
What else... oh! "Houston," as in Houston Street, is pronounced HOW-stun, not HUE-stun.
There are many, many fun things to do around the 2nd Ave F stop.
VP2 is DIRECTLY adjacent to the W 4th Street/Washington Square A/C/E stop.
If you need a place to drink heavily while listening to excellent tunes, catch the L to 1st Ave, walk half a block east on 14th and turn right on Avenue A, and walk about 3 blocks to go to HiFi, the best bar in the history of ever.
And if you're going to be raging until the wee hours and you need to take the F train someplace, please note that it only runs twice every 600,000 years after, like, 10:30 PM.Hopstop
Mobile is also really helpful; it will text you subway and bus directions!