Hi OP.
I play open almost exclusively, I only switch if I come across pad blocking. There are only a few systems that have a regular and large player population, they are normally quite dangerous as you will get interdicted by occasional piracy or just straightforward ganking. Not saying it happens every time, however you have to fly as though it could happen every time. There are numerous videos out there showing how to avoid interdiction or how to handle it if you do get interdicted.
At first its a learning curve, pvp opponents generally have much better skills and engineered ships than NPC's and will often operate in squads. I would say that if you have a month under your belt and thinking of staying in open the following will help in your early days:
1. Stay out of the hi player populated systems, including community goals for the time being. (you need to do the below first)
2. I wish someone had said to me 1 month in "select your ship choice carefully" and "target your efforts toward those choices" This stops you buying every ship in game, diverting valuable resources.
3. My preferred progression if I could do it again: Sidey - Cobra - ASPX - Python. Python will carry 180T with full shields, HRP and MRP. Best ship in the game.
4. Engineering. Think about your end goal ship wise (more on that later), do you really want A rated G5 Thrusters on a Cobra? Or would you prefer to keep the rarer mats for your Python thruster upgrades? G3 can often be plenty for small, non-pvp orientated mission runners / traderers.
5. Making credits. Do the ranking up for empire and fed's, it unlocks ships you may want later in the game. This will also make you credits too. Look for delivery missions at outposts were you have become allied to a minor faction or 2. There are other ways to gather credits too but I don't use them.
6. Make sure you have enough credits to buy your next ship, get the right modules (A through E) and at least 2 rebuys. Don't sell the previous ship to do this, keep it in case you run out of credits.
7. PP. Play it if you want to or just sign up for the special modules that come with each PP faction. Read up on these as some are better than others and it takes 4 weeks to get the goodies. For instance prismatic shields are good.
8. When you are ranking up with the Feds and Empire other ships become available. Some of these are combat orientated and a good choice if you can't afford the FdL or Mamba. Research your choices before committing. This is the point when you may wish to engage fully in PvP.
9. Eventually you can afford an Anaconda. Its expensive and the rebuy leaves a hole. It is very versatile.
10. At the top end you can rank up to get the Corvette and / or Cutter. Very good ships, very expensive and big rebuys.
Finally, try a bit of everything the game has to offer. You will need to do things like 5000LY journey for Palin, certain trading for other engineers, bounty hunting etc.
Hope it helps, o7.