Look for a software program that will be educational for your child but also fun and interactive. Computer learning programs that play out like games are especially effective for young ones, as they captivate their interest and hold it.
Find workbooks and/or activity sets that will reinforce the lessons your child will learn using the software. Some software programs come with these extras, which is always a plus. If they don't, it is not hard to find elementary Spanish workbooks that will match up to the software program.
Encourage your child to interact with the software daily. New knowledge is knowledge easily lost if the time gaps between lessons are too large.
Run through the programs yourself. This way, you and your child can develop a rapport using the words and phrases learned with the software.
Incorporate your child's new language skills into everyday life. Point out various objects around the house, supermarket, etc. and have your child identify them in Spanish. This can also be done with things like weather, days of the week, telling time, etc.