1. It is okay to be sad
One piece of advice that people always hear is to celebrate Eid as it's mandatory, and of course, all obligations should be followed as per religion. However, this does not mean one can't feel sad or grief the loss of a loved one. Your feelings are valid, and you are allowed to not feel at your best this Eid. It's okay.
2. Make Duas every time you remember them
On this day of gathering and Dawats, there is no way one can't miss their loved ones who have passed away. Please set aside and say a prayer for them every time you think of them, as there is no greater relief and act than praying to God.
3. Please don't be alone, you have people who love you
Don't force yourself into isolation. It is okay to want to be alone, but please try to meet others and leave your house for a while. It might not cure you, but a little change can feel a bit better.
4. It is natural to feel this way. It's a process.
Grief is a process, so expecting it to completely disappear on Eid is unrealistic. Let all the emotions pass by, and feel all of them. On this Eid, allow yourself to feel however you do, along with going about your religious duties.
5. Indeed we belong to Allah, and indeed to Him we return(Quran 2:156)
There is no better way than to keep reminding yourself how death works, and the best way to remember where your loved one is now.
6. Take it one day at a time, don't push yourself
Every day counts, and some days are bad, and some will be better. The important thing is to not force yourself, and just live through them. On this Eid, don't force yourself to go the extra mile, you deserve the rest, and you deserve a break.