First, Mailing lists:
Send an email with just the word SUBSCRIBE as a subject and in the message to SURNAME-L-request@rootsweb.com. Replace SURNAME with the surname you are researching, type it in all CAPS. These lists are made up of people who are researching a specific name. Don't be surprised to find distant cousins on them. Don't be disappointed if you don't make an immediate connection. It would also be a good idea to join county mailing lists (NYERIE-L or TXRUSK-L). They are mailing lists for people researching in those counties. Just add the -request@rootsweb.com to the end of whatever list you want to join. The address for posting to these boards is the same, but leave out the "-request" (WOODLAND-L@rootsweb.com).

GenForum:
http://genforum.genealogy.com/
Type up a nice query to post on these sites. Try to be as specific as you can. Something like: "I am looking for information on Mary Jones, born (birthdate) (place); died (date) in (place); married John Smith (date) (place). 

Mailing List Resource Pages:
http://resources.rootsweb.com/surnames/
There are resource pages for almost every surname imaginable.

Civil War Rosters
http://userdb.rootsweb.com/rosters/

Some Texas Specific Links
Civil War Pensions
http://www.tsl.state.tx.us/arc/pensions/index.html

Texas GenWeb:
http://www.rootsweb.com/~txgenweb/
Follow the links to the counties you are researching.

Church of Latter Day Saints
http://www.familysearch.org/

Social Security Death Index:
http://ssdi.genealogy.rootsweb.com/cgi-bin/ssdi.cgi
Use the Advanced Search Feature

USGS:
http://geonames.usgs.gov/pls/gnispublic
Will help you find places.

Beginner's Guide to the Federal Census
http://www.tngenweb.org/cntylinks/tutorial.html
This will tell you how to read the Census and what you may find on it. Most County libraries have a copy of the Census records.

County Clerk addresses and phone numbers can be found at:
http://vitalrec.com/
Follow the links to the state and county you need.