Salesforce lead enrichment - Implementation

I would like to enrich all the leads that came in through our signup forms. Right now, we are just collecting 4 fields (name, email, company name and phone number). We don't make the fields mandatory and we don't block any specific data (like gmail / yahoo email IDs).

We are planning on using lead enrichment tools but having difficulties in the implementation. The apex triggers and workflow rules are not working well together.

Can someone please offer suggestions?