Google is your friend.

My honest advice would be.. To have the BEST experience in the Mara, for a first timer, use the services of a professional guide. Either join a group and go ther as an organized tour OR get a freelance guide and go to the Mara with them,in your vehicle. It will be 100% worth it for a first time visit

That said,and to answer your questions..

From Narok to the Mara the road is halfway still a rough track,and people have over time made several diversions parallel to the main road,and in as much as following a tour vehicle would be your best shot,it can also be misleading because it depends on where the vehicle is going(which side of the mara) and what gate they plan to use. There are however signages for the various lodges/camps from Narok so you can exactly get lost..

Whilst inside the Mara,there are numerous roads/tracks, most of which aren't marked,so be alert.. your chances of getting lost are high. In other KWS parks,it's easy to drive around because all roads are well signaged but the Mara being a county council managed reserve, they haven't invested in this so you either drive around blindly or follow other drivers. Tour vehicles have the advantage of the drivers being experienced,plus they use radio for communication so always know which side to go and they pass on the info to each other

My first experience as a tourist in the Mara still stands out. Lets just say.. I went by public bus from Nairobi(yes,it's doable but you've got to be open minded and travel light). We stayed in a nice camp at Talek area, then hitch hiked a gamedrive from some other guests at the camp.. Coming back to Nairobi,we were given a ride in a Landrover that kept breaking down and we slept out in the wilderness for a good 2nights,in the middle of nowhere,in serious rain,surrounded by hyenas,cheetahs and God knows what other wildlife we didn't see in the dark. It's an experience i totally & thoroughly enjoyed but i wouldn't wish the same on anyone else :)

So, if you opt for self drive.. have ample info, a map and an open mind

Talek.

Once upon a time I also was there.

Travelled all the way by public transport. Catching the bus to Talek from Narok was almost ordinary but not so the bus from Talek to Narok. That was exciting!

From my hideout, had to get to Talek by 3am when the bus left. So had to 'wake up' at midnight and navigate the landscape by moonlight but the friend was experienced.

Saw, felt, smelt and heard, perhaps even tasted lots of 'memorable' scenes that night. Why wouldn't you wish it on someone else? I would! Before they die I wish my brothers Swenani, Tycho, Symbols, Mtu Biz, Alphdoti and others (big up y'all!) experience the same.

So experience does indeed matter.

I have been there a few times, latest being july this year and here are my views.

- What is the best direction from Nairobi after Narok?

From Narok travel for about 5km towards bomet and then turn left and drive for about 2.5 hrs to sekenani gate. There is a small tarmacked section i.e about 30min on tarmac and rest is rough road though when I was there in july, they were grading the murram road.

- Charges at the gate for a vehicle
I think it was 1000 for vehicle, 1200 per adult.

- Best track or tracks to get most of the adventure
If it's for one day take the main route from sekenani gate and drive past keekorok lodge and down to the mara river. There is a rangers camp there and most people stop to take their packed lunch there. That is also the border between former transmara and narok councils. They used to charge for one to access the transmara side but the councils rejoined after new katiba to become narok county. There is still a barrier there and they will give you a receipt reading zero shillings and you should proceed into the transmara side also known as mara triangle. There are more animals in the triangle. Drive all the way to the oloololo gate but dont exit rather turn back and do your journey back to sekenani. This is because the oloololo to narok road is quite rough. By this time you'll have seen the big five.

If you will be staying within or around the park, and for more than i day, then you can do venture beyond the main route.

- Any other tip would help
You will be travelling in dec when the 1m migratory wildebeests will be in tz. However you will see some resident ones, and many other resident game. The best time to see the 1m wildebeestes is july to oct when they are in mara. However there are many other animals especially in the mara triangle all year round. This is where many documentaries are made.

Use a 4x4 since the road is rough. Smaller 4x4 can do too. I saw some xtrails, rav 4s, suzukis, marutis in there.

Spend the night at Narok so that you can start your journey early and get at sekenani gate by 9am, mara river at noon, ollololo at 2pm, and then you will have enough time to get back to sekenani and back to narok.

The mara triangle (transmara) has better roads than narok side since they hired a private org to manage it.

There is good 3G mobile network coverage within the park and i'd recommend you use google maps/gps to see where you are and also to approximate distances. You can also buy a map at the sekenani gate.