I have a few tattoos and have friends who get inked regularly. I got my first one when I graduated college with my undergrad degree.
I have had some cover ups done, and while it can be a pain in the butt, a not great tattoo is not the worst thing in the world. Just not on the face/chest/hands and it is livable, a good coverup artist can do a better one on/around it, tattoos can be removed but it can be expensive and unpleasant. All of it survivable. Honestly I would rather deal with another bad tattoo then a bad partner. There are one or two tattoos I have that honestly I would not get now if I had not gotten then, but I like them for what they are and for how they remind me of the person I was when I picked them. Probably for the same reason people keep scrapbooks.
As we grow up we make life decisions all the time, every single day. To play or study, to go out or stay in, there are always consequences and trade offs and for the most part dealing with them makes you who you are. Don't get or not get something because of what people will think of you. Personally, I view them as something that I do just for me, for how I feel when I look at them or know they are there. I didn't get to decide how a lot of my body looks, but that one little bit of skin I got to turn into art of my choosing.
The most important thing about tattooing is your health. Go to a reputable, licensed tattoo artist. Someone who had a portfolio online, who has a clean sterile shop, and who follows all health and safety regulations.
As for designing a tattoo, it helps to do your homework. A reputable artist can take your ideas and help you make a design that will work well on skin and with whatever body part you choose.
http://tattooedtruth.tumblr.com/ is the blog of a tattoo artist who does crituque, it helps to really look at a lot of tattoos and read expert opnions on them to really learn what does and does not look good on skin. This person can get harsh and snarky, but I can understand their point from an artistic perspective.
Areas where bone is close to the skin are painful to do and hard to sit for. If you don't know your career yet you can start with a location that can easily be covered by workwear. I know people who have bicep tattoos so they wear a lot of cardigans and 3/4 sleeves at work. Back tattoos are popular and can get large without being obvious all the time.
Small does not necessarily mean discret, personally I think a medium sized one in a coverable location is a lot more subtle than a tiny one in a super visible location. It also looks more ******, but that's personal opinion.