Organic chem is a challenge, there are literally hundreds of new molecules you must be able to recognize and draw and write formulas for. You get to use Table P, Q, and R as guides, but it will take a lot of practice. There are patterns to look for, and to count on, don’t try to reinvent the process. Figure out what kind of molecule it could be from Table Q and R, then count carbon atoms, and then figure out the placement of the functional groups. Go slowly, and check twice.
Methyl hexanoate (the banana ester) is my favorite molecule, you should find a couple that you like too. Then figure out similar ones, and get a solid handle on a few of these. The rest will come with practice.
Read the BASICS quick!