Albanian network of buses is not good but also expensive. Luckily, there is very good network of furgons (very cheap mini-buses) going to nearly every town in the country. My advice is to get on the furgon with the most people because that's the one that will leave first. Empty furgons don't leave until they full, which means if you get on one that's empty you could end up waiting for 45 minutes.
This is very true about furgons. they have no timetable and they depart when they are full. Also, furgon stations aren't always in obvious locations, so you need to ask around to find them, or keep an eye out for groups of white or red minivans gathered together. Riding in a furgon is easily one of the highlights of being in Albania.
A furgon is like being in a shared taxi....if you can drive a stick shift, I suggest renting a car in Tirana or wherever you're going to be in Albania for more flexibility. I think the price is around 35 eur/day so it isn't expensive.
Most of these furgons are new but they have really old ones still plying the roads of Albania. I remember when I traveled on a furgon 10 years ago, it wasn't that great. Luckily, there's quite a lot of competition in transport now so the quality of these furgons have improved. Definitely, go on a furgon because you will get to talk to meet locals.