Check different players out and their ways of developing a theme. You can start by playing variations by others, but don't stick to it. Use your own ideas and rhythmic developments also. There are Dutta's Tabla lessons and practice and Poetic drumming also besides Alla Rakha's book and they are both very good!!
The biggest free tabla database is on the austin tabla website. http://www.angelfire.com/music3/tabla ingredients for a simple solo: Play 3 kaidas with 4 or 5 paltas each and tihia. Then you can speed up to simple rela with 3 or 4 paltas and tihia add 2 or 3 tukras and a Chakradar For a more flamboyant meal begin with a spicey peshkar with 7 or 8 variations and a chakradar ending , increase your kaidas to 7 or 8 paltas. increase speed and mix in one kaida that has a rela counterpart . add a pinch of laggi for authentic flavor. Follow with 3 or 4 tukras and be sure to recite before playing . For desert add a sumptous tripoli gat. Finish off with a Formeishi chakradar.
There are a number of kaida compositions that have a rela counterpart in other words the accents of the bol remain the same yet the speed doubles up . Tisrajati Kaida example: dhatere kitadha genadha dhagena | dhatere kitadha genadhin nakena | tatere kitata kenata takena |dhatere kitadha genadhin nagena Rela switch is |dhaterekita terekitadha gerenagadhine nagateregeta | dhaterekita terekitadha gerenagadhine nagaterekita | taterekita terekitata kerenakatine nakateregeta | dhaterekita terekitadha gerenagadhine nagateregeta | This is a great zakir piece. If this is hard to play, think 1 2 3 123, when you switch to rela, the tempo must stay the same so start slow.