Starting point based on what? Do you plan to use it personally to join many large channels from FOSS projects? If so, you need to plan for a relativrly beefy VPS, like 4 core, 8gb ram, 100gb+ ssd storage.

But for small private chats with no federation a cheap minimum VPS can work.

If you want my personal recommendation I would avoid hosting Matrix. A well federated server is costly to run and not really worth the hassle and a small private chat server with bridges etc can be done equally well or better with XMPP.