From Grecee to Croatia

You don't specify how many days you have to make this trip, but by train and/or bus, I don't think you will find a way to travel from Greece to Croatia via Albania, Montenegro, Bosnia and Herzegovina in less than at least 4 or 5 days (if you are lucky).

thank you for your answer I plan make it in 15 days, just staying 1 or 2 days in some cities, thaks

The Man in Seat 61 tells you how to get from Greece to Albania and then Albania to Bari-

Train Athens to Thessaloniki then-

There are at least two daily buses between Tiranë and Thessaloniki in Greece. Tiranë to Thessaloniki is a long journey with frequent delays at the border, so it's not to be undertaken lightly. Just ask at any travel agency locally in Tiranë or Athens. Fare around €30 one-way. Departures from Tirana at 05:00 (journey time 10h30) & 08:15 (journey time 11h00). Departures from Thessaloniki at 09:00 & 20:30, journey time 9h00. To book, try ktelmacedonia.gr/en/routes/&tid=43.

Then to Bar-

Day 1, take the afternoon train from Tiranë to Shkodër (if running) and stay overnight. Take a bus if the train isn't running. On day 2, you have two options: Travel by taxi via the Han i Hot border to Podgorica in Montenegro, or travel by bus to Ulcinj then another bus to Bar in Montenegro. If you choose the taxi option, the total journey from Shkodër to Podgorica is 59.7 km, and should take about 90 minutes including the need to change taxis at the border. Each of the two taxis should cost in the region of €20. If you choose the bus option, there are three buses a day from Shkodër to Ulcinj in Montenegro via the Muriqan border crossing, at the time of writing these were 09:00, 14:15 & 16:00 (in the other direction, buses leave Ulcinj for Shkodër at 06:00, 12:30 & 16:30). There are then reasonably frequent buses from Ulcinj to Bar. Alternatively, a taxi from Shkodër to the border at Muriqan should cost about €10-€15, and a taxi from Muriqan to Ulcinj around €20-€25.

That all sounds a bit of an adventure.

RometoRio says there is a seasonal direct bus from Bar to Dubrovnik, but at least if you have now done the hard section via and through Albania people here will know how you get up through Montenegro to Bosnia, Croatia and Slovenia.

thank you, yes sounds like an adventure

A chance find - there is another route from Athens to Tirana- take the normal route from Athens to Corfu, then a company called Finikas Lines runs a ferry from Corfu to Saranda in Albania. There is then a 5 hour bus journey apparently seven times a day to Tirana.
The Tirana to Shkoder bus apparently runs every hour, taking 2 hours, so a same day connection should be possible off the 9am ferry from Corfu.
Then the Shkoder to Ulcinj bus is supposedly 3 times a day allegedly at 9am, 2.15 and 4.
So you could in theory get from Athens to Montenegro in 3 days.

If you're planning to travel such distances on the ground in the Balkans, it's essential to have a flexible schedule or enough money to pay for intercity taxis when necessary, because it's not easy to obtain accurate online information about bus schedules. In Albania, simply finding out the departure point for a bus is often a challenge. Taxi costs, while much lower than they would be in western Europe, can really add up, and you'll probably run into many taxi drivers who accept only cash.

Note that Albanian ATMs charge very high fees. You can probably change currency (euros better, but US dollars also accepted) at a cost of not much more than 1%, which is a fabulous deal. I used an ILIRIA booth in Tirana but got a similar deal at an independent money changer elsewhere. Try to avoid changing money in airports and train stations. You need to balance the risk of traveling with a wad of cash against the high ATM fees. You will probably be using quite a lot of cash on this trip, and I myself would not be comfortable starting out with more than 200-300 euros or dollars. That probably will not be enough cash, which I found often necessary for hotels, restaurants and even some bus tickets, in addition to the aforementioned taxis.

Thank you for the advice, and yes I have notice that it´s a kind difficult to do this by the road, I would considere better a fly, thakn everybody for your comments