How do you reconnect with old friends?

Hello everyone, for a little background let's just say that I'm very introverted shy, rarely rech out first or ask someone to hang out and I've never been good with people not maintaining relationships.

That said i have several friends from highschool with whome i want to reconnect. With some of them i have minimal contact that is we share messages here and there for birthdays and holidays.

But i especially want to reconnect with one friend, let's call her Leila.

Leila was always a good friend with me, she's charismatic, optimistic, spontaneous and all in all great person. But we feel out of contact this year. Part of it is surely that we both now live in different cities so there are not many opportunities for us to meet, but I feel like the biggest part of it is that I've never knew how to maintain a hood and healthy friendship.

I want to send her a message but feel like it's never the right time. And even if i sent a casual "hi, how are you, what are you up to" kind of messages how do I continue texting her? Do i chek in every few days, send her *** posts, or what?

I'm lost i don't know what to do, please help