Grading before a sale can make sense for a valuable card where authentication is important or where the price difference between realistic condition outcomes is larger than every submission cost. It can also make a card easier for a dealer to price. But grading delays the sale, adds fees and shipping risk, and can return a lower result than expected. Compare recent raw sales with several plausible graded outcomes rather than using only the highest grade.
Ask a knowledgeable buyer or submission shop to identify specific condition concerns without promising a result. The person offering to buy has an incentive in the conversation, so obtain an independent opinion when the difference could be substantial. Use the grading-shop directory to find local submission help and read both the grading guide and selling guide. Selling raw may be better for lower-value modern cards, visibly flawed cards, or a collection that needs quick liquidation. If you submit, photograph the card, insure it appropriately, and preserve all paperwork so the eventual buyer can follow its history.