Photos and measurements
Photograph each room from several angles and give rough measurements. It avoids unnecessary visits and guesswork quotes.
Say who buys the materials
If you'll buy fixtures, tiles or units yourself, say so. Then every quote compares the same thing.
Give a budget
A total or hourly figure helps professionals propose realistic options. You're not bound by it.
Be clear about timing
Urgent, this week or flexible. Flexible timing usually attracts more quotes.
Compare line by line
Look at labour, materials and what's left for you to buy. The lowest total doesn't always cover the same work.