It depends on the type of extract you want to prepare. For water/aqueous extracts, generally you can choose to boil the pulverised plant material and then freeze dry the extract, or you can soak the material in the water (cold maceration) overnight or longer, and freeze dry the liquid phase. For other organic solvents I think you need to do soxhlet extraction, and then use a rotary evaporator to remove the solvent.

Dear Researcher,

It is not clear , "What is the purpose of Extraction ?" but I assume it is a phyto chemical investigation. So please note below

1. Crush  plant material (dried) up to powder.

2.Use soxlet apparatus for extraction. Extract plant material by increasing order of polarity i.e. Hexane,Pet.Ether,Chloroform,Ethyl Acetate,Acetone,Ethanol,Methanol and Hydro alcohol and finally water. at desire temperature.

3. Concentrate each and every fractions separately.

4. Go for column chromatography for further isolation of phytochemicals.

Please note Withania somnifera , Urtica are well researched herbs so review all articles before doing your experiments.

Good Luck.

@ajay sir...the  purpose of extraction is herbal  anti-cancer drug....any further suggestions. or book on extraction method  that could be referred to.

If the purpose of extraction is to make extract for anticancer activity , Then please go through some literature attached here. Aq and Alcoholic extract found most effective of these herbs.

http://europepmc.org/abstract/med/9055640

http://pubs.acs.org/doi/abs/10.1021/jf903836k

http://www.sciencedirect.com/science/article/pii/S027869151200539X

Thank you so much sir.

I think first you should search research paper for phytoconsyituent that are acting best for your purpose of study (Cancer). Then you decide which type of extraction you should follow. 

https://www.researchgate.net/deref/http%3A%2F%2Feuropepmc.org%2Fabstract%2Fmed%2F9055640

This article serve best. 

For the research purpose, soxhlet is best but you should follow counter current extraction method in different solvent.