What should i do for my cold before i go to bed?

Congestion: Try to get breathing through your nose. What wakes up many people is congestion and drainage. I recommend humidification (hot shower or using humidifier), sinus irrigation can be helpful to clear out mucus as well. Use of products with menthol or eucalyptus (like vicks) can then work to help keep clear. Avoid decongestants that often are stimulants that will negatively affect sleep.