Assuming that the other person has some real interest, no matter how small, in meeting with you but is really busy and you end up playing email tag with lame emails like “Send me some times when you are available,” then this technique will pay dividends. It almost never fails.

Almost never fails

Stop playing email tag, get meetings like an MVP!

Send an email saying: “I am going to send you three meeting invites for us to discuss ______ . Accept the one that works the best for you and reject the rest.” This works especially well when planning a trip because then you can add the urgency that you will only be in town on certain days.

Then send them three meeting invites

“Meeting with me Option #1” scheduled for Tuesday at 10 AM.
“Meeting with me Option #2” scheduled for Tuesday at 1 PM.
“Meeting with me Option #3” scheduled for Wednesday at 9 AM.

Very quickly, you will see a response typically: one acceptance followed by two or three rejections. Sometimes a tentative acceptance with a proposed new time, close to the time you had proposed.

Why does this work?

Most calendar systems will block off the time for tentative meetings, on the other person’s calendar so they and others inside their organization will be less likely to grab that slot. They will want to get the meetings that won’t work off their calendars. So it spurs them to action.
It makes it easy for the person to respond — they simply click a button rather than have to setup a meeting. In effect you have lowered the barrier for them.
You have taken away the overwhelming tyranny of too many choices and simultaneously put them in charge by presenting them with several simple options.