What is the best way to increase productivity?

Personally I use post-its and I've always a notebook nearby where I can write list of things to do, writing stuff on paper is much better than writing on a phone or computer.
Most people have a better photographic memory so writing since it's take longer you can recall it easily later on.

1)Planning the day
2) Wake up early
3) Do everything in time
4) Be positive
5) It's ok make a some mistakes
6) Just follow your goals and do it

Start the day off with a few physical excersises. Get that blood pumping. After you've made up your bed (aka finished your first task of the day) and did a small excersises morning routine after drinking water, You'll notice you have more energy throughout the day. Which invites to be more productive and keep finishing tasks.

Making a list. If there is one big thing yiu have to do, try to make it into many small steps instead of one scary thing. Easier to start this way and easier to keep going.
If you have manny things and don't know where to begin, again write a list

We need to be well prepared for the tasks ahead and have a plan to carry them out. Relying only on motivation or will power in the last minute can backfire.

I think the best way is to remove distractions. For me, I’m always destructed by my phone, figures on my desk, and sometimes my lap top! So what I do is I put everything away (minus my lap top if I need to use it) and work. If I’m doing something on my lap top I limit myself to a few NECESSARY tabs! I hope this helps!

to abstain or minimize unproductive habbits like browsing on your phone in your spare time or sitting down behind your pc or tv when you think you have nothing important to do

You should log your time and make sure where your time has gone. Another thing is rather than logging your time, you should look back your actions each night and then change where your time has gone. I normally do that. I also use a planner to organize my tasks.