Because there is no need to take extra time away to travel to a meeting, this gives one the opportunity to register for more meetings than ever before.
Keep a calendar of meeting dates for those societies that interest you the most so that you know ahead of time which ones you would like to attend. You can assume that any meeting between now and July will be virtual.
If you are simply attending, find out when the networking sessions are and what sort of "rooms" are available for chatting with people.
If you are presenting research, your prep work should not be different than what you would have done previously, which is to practice practice practice and get feedback on your slides and presentation from your mentor/advisor and others first before you record or present live. Most presentations are recorded now so you have the advantage of really perfecting it. Have someone ask you a question in the Q+A section so that it gets the conversation started, some people may then feel more comfortable asking a question as well.
You should ask questions as well of other presenters in the area of your research to take advantage of the opportunity.