Too often I find people are sparklingly clear about what will be different about their spouse, their children, or their boss... "Oh, she won't be such a relentless nag" or "He won't be such a massively royal pain in the ass..." It gets a little...fuzzier....when asked how they, themselves, will be different, but good therapy isn't usually about changing the people around you. Usually, its about deepening and challenging the way you, yourself, have learned to operate and communicate in the world around and inside of you. A good therapist will work with you to raise your own personal standards about how you treat yourself and others, and what you are willing to tolerate in return. What therapy isn't about is getting the people around you to lower their standards and learn to tolerate disrespectful behavior from you.
Articulate your goals to your therapist, and take responsibility for staying on course with these goals. If you don't feel you are being heard, or challenged, share that directly with your therapist. Don't use therapy as another place where you don't take responsibiility for getting your needs met.
Which brings me to the next tip....
3) Your therapist is a) not a mindreader, and b) is responsible for taking care of their own feelings.
Check in with your therapist about what is and what isn't working in your work together. Don't expect him or her to know this. Along those lines, don't withhold important information from your therapist. For example, if you are having an affair or self-medicating with alcohol or food, be brave and share. What you don't share can define your relationship and sabotage your goals. And remember, your therapist is not there to judge you but to help you grow as a fellow human being (and whom has their own challenges along the way too).
If you tend to be a caretaker outside of your therapist's office, you might find yourself wanting to play this role in his or her office as well. Don't. Your therapist is responsible for taking care of their own feelings. I've heard more than once people say things like "Well, I didn't want to hurt his feelings." Even if you say something that the therapist strongly disagrees with or their feelings are wounded, you should always feel you are encouraged to have a dialogue about that without in any way feeling its your job to caretake your therapist. If your therapist becomes defensive or responds in a way that makes you feel unsafe or attacked, share that in the moment. If the dialogue isn't a respectful, productive one, you may need to assess immediately if the boundaries are safe.
4.) Be open to real feedback.
There is a difference between being criticized by your therapist, and being given feedback by him or her that might make you uncomfortable but will allow you to grow into a more relational, respectful, authentic, and mature human being.