Slot free roll is basically of three types. https://planposition.com/ One is where you play for a fixed time period. Another one is where you get a no deposit bonus. The last one is a free roll slot tournament where you compete to win cash prizes. You just need to look for the site that offers you maximum benefits so that you can win a good amount.
In the first kind of free roll, you get a slot machine and some credit points for affixed time. You have to play within this time and spend all your chips. All players get same time and same number of credits. After the time is over, all your unused chips are lost. Your winning amount is calculated and you get money according to the credits you won.
If you go for multiple levels then your credits are carried forward and you your winning credits are calculated in the end of the game. If you search online for some casinos then you can find out which casino offers you the best prize.
Then there is free roll slot where you get free credits to play on slot machines. Only thing is that here the amount of credit is very low. But still it is good if you win some cash from almost nothing. You can always win some extra chips if luck favors you.
There are some slot tournaments, which give you a chance of winning not only cash but also other prizes. These tournaments are fun to play and also you get to compete with all kind of players. With players of different levels and experience playing together, the fun and excitement of competition doubles.