Advice for level 1 homebrew campaign

Hello everyone! I just finished dm'ing a pre written module and it was my first time as a Dm. I am now getting the itch to run a homebrew campaign in my own setting. I have an overall handle on making my world and fleshed out the starting area. My main question is- Should I run a few starter/side quests that really do not link to anything and see what my party likes then flesh out the story from there and maybe create a bbeg based on how the interact with things those first few sessions OR should I know what my bbeg is first and then have everything link (as best as possible because we all know nothing goes as planned in DND). This will start at level 1 and I am planning on a long term campaign. 

Any advice is greatly appreciated!

in my opinion you should start with the miscellaneous starter quests while having a basic bbeg idea and shape it according to your parties choices

at least that's what I have done sometimes. other times I improvised almost everything from a basic outline  

Thank you! 

Rather than deciding on a BBEG right off the bat, I would suggest deciding on a theme first. Then make a short list of what sorts of BBEGs might fit that theme. Then, as BTB suggested, toss a bunch of plot hooks at the players to see which ones they bite on. Develop the plot in response to the attention that the players show toward certain hooks or certain NPCs. And make a note of which NPCs the players grow attached to, so you can devise ways to make them either agents of the BBEG who will turn on the players, or victims of the BBEG who will be sacrificed to propel your players into the Final Battle.

Try to write in your character's backstories into the campaign. Like suggested above, it is also good to get a general idea of what the campaign's theme will be (High Fantasy, Horror). Another thin to do that I wished I had done with my players was to have them create connections on how they know some or all of each other. It opens up roleplaying opportunities and makes it much easier to start without going through the process of having them come together as a group-they already know each other. 

For a start, I recommend having them do some odd jobs, delve into some dungeons, and do a couple other things that seem rather unrelated, but drop some foreshadowing or hooks into later ideas you have and maybe some future planned villains.