hello! I am a new plant owner that is known for having a black thumb.

I would like to get into houseplants. Is it better to buy small young plants or large mature houseplants?

I know that plant goes into shock from going from a nursery into a home. And my house doesn't have great light or temperature. So it is already a hardship to own plants. I did not know if a mature plant is more hardy or does it have a harder time to adjust to being inside.

HI,
The size of the plant isn't going to make much difference. I think you can spend $4 on a little one and have it die sooner, only because it has less 'reserve' (which is how it seems to me, little plants can dry out suddenly, or $10 may last longer.. but the best KIND of plant will last longest. Let's help you make the best choice.
Sounds like you think the light is very low (dim) right? What kind of light can you give a plant?

I have a lot of trees outside my windows. It is bright enough for me to comfortably read a book without lights on, but I would still classify it as low light. I have heard pothos are pretty good beginner plants.

Pothos might do ok, they are a good one to try for sure. Peace lily also. I like about a six inch pot size. Bigger is ok if you like. I dont buy bigger because I figure my plant might grow bigger anyway. If it likes the place, it can stay in that pot for a long time. You can set that inside a nice pot or basket. No need to fertilize.

with what Sally has posted. I would add that the most common mistake made by folks new to caring for indoor plants is repotting them unnecessarily. It is best to keep your new plants - regardless of size - in their plastic nursery pots so the soil and roots remain undisturbed. If you want something more attractive, the plastic pot and plant can be double-potted into something more attractive.

The lower the light, the less water the plant uptakes. The main killer of indoor houseplants seems (at least for me) to be overwatering. If the light isn't optimal, the plant doesn't use or need as much water as one that is actively growing in good light. I would wait until the plant is light in its nursery pot (i.e. .. dry) before giving a good watering and letting it drain out completely. Let it dry out again before watering. In lower light, you may only be watering every couple of weeks..or once a month ... it's hard to say. Everyone always says sansevierias (now in the draceana genus but I'm resisting) are easy, but they give me fits for that very reason. My house has few spots with decent light and if I water them more than about once a month, they keel over.