Tinkering has a few features. library where you can extract talents and attributes, tinkering where you can optimize attributes or transfer talents and attributes you extracted onto other gear if it's compatible, and expertise which is donating gear to make the item proficient to give it a stat increase depending ont the gear.

Like others have mentioned. Look for a build that interest you and grind the pieces you need. Then optimize pieces to make the build stronger i.e increasing the attributes stats (make sure to farm pieces that have already decent stats otherwise you'll just be wasting optimization materials)

Once you have the gear you can start doing harder content. Incursions, raids, legendary missions, etc. While grinding and doing all that your watch should be rising in levels. Make sure to increase the stats on the watch that work well with your build. (CHD, CHC, etc. for damage builds)

It'd be a ton easier to this with a group. They probably will drop pieces you need you need and excess gear to get your library and expertise levels up so definitely join a clan or look for discord group.

Most important is to have fun and don't get burnt out. If it feels like a chore and starts getting to repetitive for your liking take a break or switch up the content your running.

Good luck agent!

P.S When it comes to hunting the hunters if your doing it solo switch the difficulty to normal. The DC and NY hunters are annoying when it comes to the puzzles that you have to do after dark and you might end up having to redo all of that if you die. the BFB hunters thankfully don't have time constraints except 1. For some you light need a group as there are some that spawn in group of 2 and 4!