Be familiar with splitting patterns on HNMR. For example if you have butane, \/\ , you will have a triplet of 6 hydrogens, and a quartet of 4 hydrogens. The triplet represents the 2 CH3 groups attached to a carbon with two hydrogens. Remember, the number of peaks of a triplet or quartet always indicates the number of hydrogens on an adjacent carbon MINUS 1.
Also, for HNMR, you should be familiar with some key peaks. 0 ppm is always TMS, the solvent. a peak around one is an sp3 hybridized carbon (your RCH3s), a peak at 2 is a RHC-O, peak at 12 is carboxylics, 10 is aldehydes.
CNMR: number of peaks = number of UNIQUE carbons. The higher the ppm, or further
downfield, the carbons, the more stuff is going on. These spectrums are usually given in addition to HNMR, to further narrow choices. Some unique peaks: 180-190 aldehydes and ketones; 150-170 carboxyls, esters, amids, 100-120 sp2 hybrized, 80-90 sp hybridized, and 10-30 sp3 hybridized. So just count the peaks, that equals nubmer of carbons, and fix it into the answers. Make sure you dont count the TMS peak at 0 ppm.
IR: make sure you know the principle behind this. Blast the sample with Infared Radiation, bend and stretch at different frequencies. The more downfield you go (higher numbers) there is more stretching. Key peaks, 3200 - 3500 is OH or NH. OH is very broad and NH is usaully sharper with two peaks. A carboxylic acid is HUGE in this area, along with amides, usually going to 2800 and with a C=O at 1700. the mass of peaks between 3200-2800 is just different hybridizations of C-H. probs never need to know the difference between them. Also, 2100 is C triple bond to N or C triple bond to C. 1700 is C=O. 1500 and 1600 represent aromatic rings, but depending on the deshielding effects and proximity to electronegative groups, the C=O group could shift this way. Everything below 1500 is called the 'fingerprint region.' A
skilled organic chemsit can determine these peaks and crazyness. But normally it is just junk and you shouldnt even give a half second thought to it. (if you have an ether, it wll be about 1200 with either a deep peak, broad beak, multiplet, depending on what else is around it).
Also know some stuff about UV/VIS. the different paths a electron can relax by. And the difference between excitation, relaxing, flourescence and photoplourescents
*NOTE: you said alkene or alkynes are at 3000 for IR. but that is wrong.
If you want to practice looking at real molecules on IR or HNMR , go to sigma-aldrich and type in the molecule IUPAC name.
http://www.sigmaaldrich.com/united-states.html
Hope this helps!
