I just did a music clinic at a local elementary school and the teacher thanked me afterwards and said that the biggest thing that she would take away from it was to remind the students to "bring the instrument to you." It is a simple concept but an essential one. We all stress proper posture but what we can forget to remind the students is that the instrument comes to you and that you do not go to the instrument. If you are sitting at the front of the chair, with your feet on the floor, your back straight, and you are relaxed (think of being suspended by a string, like a puppet or marionette) you are ready to receive the instrument. Then, all you need to do is bring the instrument to your embouchure for brass and reed players. Too often, bad posture if the result of the students moving to the instrument, where ever it is held, e.g., the left, the right, downwards or upwards. So sitting "properly" but relaxed and "bringing the instrument to you," eliminates a lot of problems, especially for trombones, trumpets, saxophones, and clarinets. Flutes, euphoniums and tubas need a bit more instruction with posture. French horn players need special instruction. Keep it simple and you will be simply astounded by the results. 

For me, I am going to strive to mix-up my practicing - keep it fresh: tongue what I used to slur, sit when I used to stand, improvise when I used to run scaler patterns, etc. Just as weight lifters keep their body guessing in the gym, I think you need to change up your routine to achieve the greatest gains in your practicing. If you do not, I think you can get in a "rut" and plateau in your improvement. Small (e.g., sitting and standing) and large changes (e.g., different warm-up routines or even skipping the warm-up some days) are needed to make significant gains. It is also important to take breaks when you practice. Use that time to do other important things, like compose, arrange, exercise, or do other work. Your embouchure and your mind needs a break. Here's hoping you make great strides this year. I too hope to move forward with my playing.