Start by deciding your long term plan. Do you want to study, then come back and work in India? or do you want to find work and then settle abroad? Once you decide on that, you can then look at at whatever place you think will be best and start preparing for those.
If its the US, then its advisable to prepare for GRE and TOEFL. For other countries IELTS.
Next comes the matter of money. Education abroad is expensive for the big 4(US, UK, Canada, Australia). So if you are going for one of those, then start arranging your money well beforehand. I do want to tell you something.
I dont know if you are aware of it, but you can get quality education at much cheaper prices in Europe and I’ve also heard good things about education in Singapore, Malaysia etc. So dont just blindly go for the big 4 and study your options carefully. Personally I would push you to look at Germany. They have many good PG courses that are very cheap compared to other places. You would only have to show funds for accomodation and food.
However just because they are cheap, dont think they will be worthless or easy to complete. Wherever you decide to go, be prepared to put in a lot of hard work.
The rest is all mental preparation and patience. If you’ve never gone abroad before, then prepare to go there with an open mind. Read all about the place you are going to. Theres plenty of advice on that here in Quora for every place in the world.
Hope I helped. If theres something specific you want to ask, feel free to ask me in comments
