In addition to all of the very good advice in this thread, I will add I am a big fan of Dollar Cost Averaging. If you have a large amount to put into the market, don't put it in to whatever fund you decide all at once, put it in on a monthly basis. This protects you, to some extent, from the market taking a dump the day after you buy, because you are always buying. And your cost at the end is an average of all the times you bought in, and is not so much tied to prices on the day you bought in.

This may involve some planning for moving money around, because you will want to keep the remainder in a good HYSA in the meantime.