Hi there! I bought a trezor t on march 2021 using some btc, i never opened it, now i'm thinking about starting investing a little bit, basicly holding some cryptos i like, but i don't know if it is worth to keep this trezor t or sell it and buy the new one or another kind of hardware wallet. Some advices are appreciated, peace.
Well done! Really! Most just go head first into issues. Having a hardware wallet and also asking is a very good way to go.
As the others said, you should update the firmware. It's important, please don't miss this.
Also as others said, you should keep the backup seed safely. But I will say some more things:
1. Make sure it's you who generate a new seed on your device.
2. The seed must be written down and stored safely offline and preferably in at least two places, geographically separated.
3. Maybe it's overkill, but I've seen cases this could have been avoiding other issues: after everything is set up and you can see (write down/copy-paste) your first address or few addresses (I use my hardware wallet with Electrum and there this is easier) reset the hardware wallet again, restore from the written down seed and see if you've got the same addresses. Especially since it's expected you may play around a little with your Trezor it's better to be 100% certain the seed you'll be putting to safety is indeed the one the Trezor has in use.