Need to upgrade TYPO3 version 6.1.7 to latest version -

i working on typo3 version 6.1.7 , requirement upgrade latest version.

1. what have keep in mind or consider while upgrading version?

2. how can upgrade typo3 version?

see https://docs.typo3.org/typo3cms/installationguide/latest/upgrade/ further details on upgrading. it's possible select different target versions 7.6 or 6.2 in documentation well...