I'm starting an audio production (music and sound design) for a TV series.
I wonder if someone who has experience in this kind of work, would give me tips on best audio mastering techniques for TV, since most people do not use a home-theater and are just satisfied with the sufferable TV speakers?

The best thing to do is find out what the series producers want. Do they even want you to master it? Or would they prefer raw tracks or stems?

Put some compression on every track and then a little more on the master buss. I really like the "Concrete Limiter" in Prochannel for this with the LP-64 on the master.   It use to be that mixers in the biz cut off everything below 250hz,  but i think it's 80hz now days.  Don't have big, loud important audio on frame one (old days you wanted audio to start 15 frames in, but it's much less now).  In the beginning, always check your mixes on small, crappy speakers at very low volumes until you have trained your ears enough. 
 
I hate to say this, but you want your mixes to sound as "loud" as you can make them.  That way you sound better than other channels that people flip too with the touch of a button.
 
I use to mix TV shows, but it has been 20 years.
 
Congrats and Good Luck! 

It blows my mind how good a concert on tv can sound coming out of an unassisted Samsung 48" tv. Those guys really know what they're doing.